Work vehicle automatic traveling system

ABSTRACT

A work vehicle automatic traveling system includes a route element selecting unit that, on the basis of state information, sequentially selects a next travel route element on which a work vehicle is to travel next, from a travel route element set and a circling route element set. The route element selecting unit includes a cooperative route element selection rule, which is employed when a plurality of work vehicles carry out work travel cooperatively in an area CA to be worked, and an independent route element selection rule, which is employed when a single independent work vehicle among the work vehicles carries out work travel independently in the area CA to be worked. Also described is selecting the next travel route element based on the independent route element selection rule.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the United States national phase of InternationalApplication No. PCT/JP2017/042873 filed Nov. 29, 2017, and claimspriority to Japanese Patent Application No. 2016-245801 and 2016-245803filed Dec. 19, 2016, and Japanese Patent Application No. 2017-221342filed Nov. 16, 2017, the disclosures of which are hereby incorporated byreference in their entirety.

TECHNICAL FIELD

The present invention relates to a work vehicle automatic travelingsystem for a plurality of work vehicles that carry out work travelcooperatively in a work site while exchanging data.

BACKGROUND ART

A field working machine disclosed in Patent Document 1 includes a routecalculating part and a drive assist unit for working a field whiletraveling autonomously. The route calculating part finds the outer shapeof the field from topographical data, and on the basis of the outershape and the work width of the field working machine, calculates atravel route that starts from a travel start point to a travel end pointthat have been set. The drive assist unit compares a host vehicleposition found on the basis of positioning data (latitude/longitudedata) obtained from a GPS module with the travel route calculated by theroute calculating part, and controls a steering mechanism so that thevehicle body travels along the travel route.

While Patent Document 1 discloses a system that controls the autonomoustravel of a single work vehicle, Patent Document 2 discloses a systemthat causes two work vehicles to work while traveling in tandem. In thissystem, a positional relationship of a second work vehicle relative to afirst work vehicle is set after a field has been specified, and travelroutes for the first work vehicle and the second work vehicle to workare then determined. Once the travel routes are determined, the firstwork vehicle and the second work vehicle measure their own positions andwork while traveling along the travel routes.

PRIOR ART DOCUMENTS Patent Documents

-   Patent Document 1: JP 2015-112071A-   Patent Document 2: JP 2016-093125A

DISCLOSURE OF THE INVENTION Problems the Invention is to Solve

[1] One problem pertaining to the above-described background art is asfollows.

If a plurality of work vehicles carry out work travel in a work site,the work time can be shortened. To realize this, an autonomous travelsystem such as that disclosed in Patent Document 2 sets a workdeployment position of the second work vehicle with respect to the firstwork vehicle in advance, and in principle, the two work vehicles carryout work travel while maintaining the work deployment positions thathave been set. However, this does not take into account a situationwhere one of the first work vehicle and the second work vehicle departsfrom the work travel for some reason. If only one of the first workvehicle and the second work vehicle has departed, either the remainingwork vehicle will also depart from the work travel, or the remainingwork vehicle will carry out work travel along its own travel route,which has been provided in advance. In actual work travel, mechanicalfactors such as refueling or unloading harvested crops, environmentalfactors such as weather changes or the state of the work site, and thelike arise during work travel in a large field, and situations where awork vehicle departs from the pre-set work travel will eventually arise.

In light of such circumstances, what is needed is a work vehicleautomatic traveling system capable of appropriately handling thedeparture of a work vehicle from work travel, when a plurality of workvehicles carry out cooperative work travel in a work site.

[2] Another problem pertaining to the above-described background art isas follows.

When only a single work vehicle carries out work travel in a work site,there is no danger of collisions with other work vehicles. Furthermore,even if a plurality of work vehicles carry out work travel in a worksite, an autonomous travel system such as that disclosed in PatentDocument 2 sets a work deployment position of the second work vehiclewith respect to the first work vehicle in advance, and in principle, thetwo work vehicles carry out work travel while maintaining the workdeployment positions that have been set. Thus as long as the first workvehicle and the second work vehicle do not depart from the set travelroutes, there is little risk that the first work vehicle and the secondwork vehicle will become abnormally close to each other or collide witheach other. However, maintaining work deployment positions that havebeen set in advance limits the freedom of the work travel by theplurality of work vehicles. This makes flexible work travel thatresponds to the work environment impossible. However, in actual worktravel in a large field, it is often necessary to depart from thepre-set travel route, change the travel route partway through the work,and so on due to changes in the work environment of the work vehiclecaused by mechanical factors such as refueling or unloading harvestedcrops, environmental factors such weather changes or work siteconditions, and so on.

In light of such circumstances, what is needed is a work vehicleautomatic traveling system capable of responding to changes in the workenvironment. When a plurality of work vehicles are introduced, it isimportant to prevent the work vehicles from becoming abnormally close toeach other or coming into contact with each other, while at the sametime increasing the freedom of the work travel by the work vehicles.

Means to Solve the Problems

[1] A solution corresponding to problem [1] is as follows.

A work vehicle automatic traveling system, which is for a plurality ofwork vehicles that carry out work travel cooperatively in a work sitewhile exchanging data, includes: an area setting unit that sets the worksite to an outer peripheral area, and an area to be worked on an innerside of the outer peripheral area; a host vehicle position calculatingunit that calculates a host vehicle position; a route managing unit thatmanages a travel route element set and a circling route element set soas to be capable of readout, the travel route element set being anaggregate of multiple travel route elements constituting a travel routethat covers the area to be worked, and the circling route element setbeing an aggregate of circling route elements constituting a circlingroute that goes around the outer peripheral area; a route elementselecting unit that, on the basis of state information, sequentiallyselects a next travel route element, on which the work vehicle is totravel next, from the travel route element set, or a next circling routeelement, on which the work vehicle is to travel next, from the circlingroute element set; and an autonomous travel controlling unit thatexecutes autonomous travel on the basis of the next travel route elementand the host vehicle position. Furthermore, the route element selectingunit includes a cooperative route element selection rule employed whenthe plurality of work vehicles carry out work travel cooperatively inthe area to be worked, and an independent route element selection ruleemployed when one of the work vehicles acts as an independent workvehicle and carries out independent work travel in the area to beworked. In this work vehicle automatic traveling system, when theindependent work vehicle is carrying out independent work travel in thearea to be worked, and a work vehicle aside from that vehicle iscarrying out circling travel based on the circling route element or isstopped, the route element selecting unit of the independent workvehicle selects the next travel route element on the basis of theindependent route element selection rule.

According to this configuration, first, multiple travel route elementsthat create a travel route covering the area to be worked, and circlingroute elements that create a circling route going around the outerperipheral area, are calculated. Under the cooperative route elementselection rule, the travel route elements are selected so that theplurality of work vehicles carry out work travel cooperatively in thearea to be worked. Under the independent route element selection rule,the travel route elements are selected so that the independent workvehicle carries out independent work travel in the area to be worked.Under the cooperative route element selection rule, if, for example,while two work vehicles are carrying out work travel, one of the workvehicles deviates from the work travel, the other work vehicle mustcarry out the work travel in the area to be worked independently. Inthis case, the rule is switched from the cooperative route elementselection rule to the independent route element selection rule, and theindependent route element selection rule is applied to the selection ofthe travel route elements of the work vehicle carrying out independentwork travel. As a result, the work vehicle carrying out independent worktravel carries out the work travel in the area to be worked so as toalso include the work travel of the work vehicle that has deviated, andthus the work can be completed in the area to be worked without leavingunworked areas.

The travel route element sets that create travel routes covering thearea to be worked include a mesh line set and a parallel line set. Themesh line set is an aggregate constituted by mesh lines that divide thearea to be worked into a mesh, and a point of intersection between meshlines is set as a route changeable point where the route of the workvehicle is permitted to be changed. The parallel line set is anaggregate constituted by parallel lines that are parallel to each otherand divide the area to be worked into rectangular shapes, and movementfrom one end of one travel route element to one end of another travelroute element is executed through U-turn travel in the outer peripheralarea. The ways in which routes are selected under the cooperative routeelement selection rule and the cooperative route element selection rulediffer for the mesh line set and the parallel line set. In thecombination of the mesh line set and the cooperative route elementselection rule, the next travel route element is selected so that acompound spiral-shaped travel trajectory created by a plurality ofspiral-shaped travel trajectories by the work vehicles covers the areato be worked. In the combination of the mesh line set and theindependent route element selection rule, the next travel route elementis selected so that a spiral-shaped travel trajectory by the independentwork vehicle covers the area to be worked. Accordingly, even if the worktravel transitions from work travel by a plurality of work vehicles towork travel by a single work vehicle, the work in the area to be workedcan be carried out smoothly, without leaving unworked areas.

In the combination of the parallel line set and the cooperative routeelement selection rule, if a given work vehicle has stopped in the outerperipheral area, that work vehicle may obstruct the U-turn travel ofanother work vehicle, depending on the position of the stopped workvehicle. In light of this, in the combination of the parallel line setand the cooperative route element selection rule, the travel routeelement where a work vehicle aside from the host vehicle is located, anda travel route element adjacent to the stated travel route element, areexcluded from being selected as the next travel route element.Additionally, in the combination of the parallel line set and theindependent route element selection rule, the travel route elementmoving toward the work vehicle aside from the host vehicle, located inthe outer peripheral area, is excluded from being selected as the nexttravel route element. As a result, even if one of a plurality of workvehicles carrying out cooperative work travel has stopped at a location,in the outer peripheral area, that obstructs the U-turn travel ofanother work vehicle, the selection of the travel route elements ischanged as an exceptional process, which realizes work travel havinglittle downtime.

[2] A solution corresponding to problem [2] is as follows.

A work vehicle automatic traveling system, for a plurality of workvehicles that carry out work travel cooperatively in a work site whileexchanging data, includes: a host vehicle position calculating unit thatcalculates a host vehicle position; a route managing unit thatcalculates a travel route element set, the travel route element setbeing an aggregate of multiple travel route elements constituting atravel route covering the area to be worked, and stores the travel routeelement set so as to be capable of readout; and a route elementselecting unit that selects a next travel route element, which is to betraveled next, sequentially from the travel route element set, on thebasis of the host vehicle position and a work travel state of anothervehicle.

According to this configuration, the travel route element set, which isan aggregate of multiple travel route elements, is calculated before thework, as a travel route covering the area to be worked. Furthermore,because data can be exchanged among the work vehicles, the work travelstate of another vehicle can be read out from data indicating the worktravel states of the work vehicles, which is included in the exchangedata. Each work vehicle executes work travel along the travel routeelements selected sequentially from the travel route element set. Atthis time, each work vehicle selects the next travel route element to betraveled on while taking into account the position and the work travelstate of the host vehicle. This makes it possible to carry outautonomous travel taking into account the behavior of other vehicles,even while executing work travel with a high degree of freedom.

According to one preferred embodiment of the present invention, an othervehicle positional relationship indicating a positional relationshipbetween the host vehicle and another vehicle is included in the worktravel state of the other vehicle, and the system further comprises another vehicle positional relationship calculating unit that calculatesthe other vehicle positional relationship. According to thisconfiguration, the work vehicle selects the next travel route element tobe traveled on the basis of the other vehicle positional relationship,which indicates the positional relationship between the host vehicle andthe other vehicle. Accordingly, the work vehicle can travel whilekeeping a distance from the other vehicle at a set range or more, travelwhile avoiding another vehicle that has temporarily stopped, and thelike.

Furthermore, according to one preferred embodiment of the presentinvention, the other vehicle positional relationship calculating unitcalculates an estimated contact position between the work vehicles onthe basis of the other vehicle positional relationship, and when theestimated contact position has been calculated, the work vehicle thatwill pass the estimated contact position at a later time is temporarilystopped. According to the work vehicle automatic traveling systemconfigured in this manner, one of the work vehicles can be temporarilystopped before reaching a position where the host vehicle and the othervehicle will come into contact. At that time, the work vehicle thatpasses the estimated contact position at a later time is stopped, andthe work vehicle that passes the estimated contact position at anearlier time passes the estimated contact position first. This providesan advantage of reducing the amount of time for which the work vehicleis stopped. Furthermore, the work vehicle can cancel or prohibit theselection of a travel route element leading to the position where thehost vehicle and the other vehicle will come into contact.

According to this work vehicle automatic traveling system, a workvehicle can not only obtain the position of the host vehicle and theposition of the other vehicle from the other vehicle positionalrelationship, but can also obtain the travel route elements selected bythat host vehicle and the travel route elements selected by the othervehicle through mutual data exchange. If the travel route elementsselected by the host vehicle and the other vehicle include places thatintersect or are near each other, those places can be extracted ascandidates for estimated contact positions. Furthermore, the likelihoodof contact between the host vehicle and the other vehicle can beestimated accurately from the current positions of the host vehicle andthe other vehicle in the respective selected travel route elements. Assuch, according to one preferred embodiment of the present invention,the other vehicle positional relationship calculating unit calculatesthe estimated contact position on the basis of the other vehiclepositional relationship, and the travel route elements where theplurality of work vehicles are traveling.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram schematically illustrating work travel of a workvehicle in an area to be worked.

FIG. 2 is a diagram illustrating the basic flow of autonomous travelcontrol using a travel route determination device.

FIG. 3 is a diagram illustrating a travel pattern of repeating U-turnsand straight travel.

FIG. 4 is a diagram illustrating a travel pattern that follows amesh-shaped route.

FIG. 5 is a side view of a harvester serving as one embodiment of a workvehicle.

FIG. 6 is a control function block diagram for a work vehicle automatictraveling system.

FIG. 7 is a diagram illustrating a method of calculating mesh lines,which are an example of a travel route element set.

FIG. 8 is a diagram illustrating an example of a travel route elementset calculated by a rectangular part element calculating unit.

FIG. 9 is a diagram illustrating a normal U-turn and a switchback turn.

FIG. 10 is a diagram illustrating an example of the selection of atravel route element in the travel route element set illustrated in FIG.8.

FIG. 11 is a diagram illustrating a spiral travel pattern in a travelroute element set calculated by a mesh route element calculating unit.

FIG. 12 is a diagram illustrating a linear back-and-forth travel patternin a travel route element set calculated by the mesh route elementcalculating unit.

FIG. 13 is a diagram illustrating the basic principle of generating aU-turn travel route.

FIG. 14 is a diagram illustrating an example of a U-turn travel routegenerated on the basis of the generation principle illustrated in FIG.13.

FIG. 15 is a diagram illustrating an example of a U-turn travel routegenerated on the basis of the generation principle illustrated in FIG.13.

FIG. 16 is a diagram illustrating an example of a U-turn travel routegenerated on the basis of the generation principle illustrated in FIG.13.

FIG. 17 is a diagram illustrating an α-turn travel route in amesh-shaped travel route element set.

FIG. 18 is a diagram illustrating a case where, after departing an areato be worked, the work travel does not resume from the work travel thathad been carried out before departing from the work travel.

FIG. 19 is a diagram illustrating work travel by multiple harvesterssubjected to cooperative control.

FIG. 20 is a diagram illustrating a basic travel pattern incooperatively-controlled travel using a travel route element setcalculated by the mesh route element calculating unit.

FIG. 21 is a diagram illustrating departure travel and return travel incooperatively-controlled travel.

FIG. 22 is a diagram illustrating an example of cooperatively-controlledtravel using a travel route element set calculated by the rectangularpart element calculating unit.

FIG. 23 is a diagram illustrating an example of cooperatively-controlledtravel using a travel route element set calculated by the rectangularpart element calculating unit.

FIG. 24 is a diagram illustrating a middle dividing process.

FIG. 25 is a diagram illustrating an example of cooperatively-controlledtravel in a field that has been divided in the middle.

FIG. 26 is a diagram illustrating an example of cooperatively-controlledtravel in a field that has been segmented into a grid shape.

FIG. 27 is a diagram illustrating a configuration in which slaveharvester parameters can be adjusted from a master harvester.

FIG. 28 is a diagram illustrating autonomous travel for creating aU-turn travel space near a parking position.

FIG. 29 is a diagram illustrating a specific example of route selectionby two harvesters having different work widths.

FIG. 30 is a diagram illustrating a specific example of route selectionby two harvesters having different work widths.

FIG. 31 is a diagram illustrating an example of a travel route elementset constituted by curved parallel lines.

FIG. 32 is a diagram illustrating an example of a travel route elementset including curved mesh lines.

FIG. 33 is a diagram illustrating an example of a travel route elementset constituted by curved mesh lines.

BEST MODE FOR CARRYING OUT THE INVENTION Overview of Autonomous Travel

FIG. 1 schematically illustrates work travel of a work vehicle in a workvehicle automatic traveling system. In this embodiment, a work vehicleis a harvester 1 that, as work travel, carries out harvesting work(reaping work) for harvesting crops while traveling, and is a modeltypically called a normal-type combine. The work site where theharvester 1 travels for work is called a field. During harvesting workin the field, the area that the harvester 1 circles the border lines ofthe field, called a “ridge”, is set as an outer peripheral area SA. Theinner side of the outer peripheral area SA is set as an area CA to beworked. The outer peripheral area SA is used as a movement space for theharvester 1 to unload harvested crops, refuel, and the like, as a spacefor switching directions, and so on. To set the outer peripheral areaSA, the harvester 1 circles the border line of the field three or fourtimes as initial work travel. In the circling travel, the field isworked by an amount equivalent to the work width of the harvester 1 witheach pass, and thus the outer peripheral area SA has a widthapproximately three to four times the work width of the harvester 1.Accordingly, unless specifically indicated otherwise, the outerperipheral area SA is treated as an already-harvested site (analready-worked site), whereas the area CA to be worked is treated as anunharvested area (an unworked site). Note that in this embodiment, thework width is handled as a value obtained by subtracting an overlapamount from a reaping width. However, the concept of the work widthdiffers depending on the type of the work vehicle. The work width in thepresent invention is defined by the type of the work vehicle, the typeof the work, and so on.

Note that the term “work travel” used in this application is used notonly in reference to travel executed while actually carrying out work,but with a broader meaning encompassing travel carried out to changedirections during the work, in a state where work is not being carriedout.

Furthermore, in this specification, the term “work environment of thework vehicle” can include the state of the work vehicle, the state ofthe work site, commands from a person (a monitoring party, a driver, anadministrator, or the like), and so on, and state information is foundby evaluating the work environment. Mechanical factors such as refuelingand unloading harvested crops, environmental factors such as changes inweather and the state of the work site, and furthermore, human requestssuch as unanticipated commands to suspend the work, are included in thestate information. When a plurality of work vehicles carry out worktravel cooperatively, state information of another vehicle is handled asa work travel state of the other vehicle, and an other vehiclepositional relationship indicating a positional relationship between thehost vehicle and the other vehicle is also included in the work travelstate of the other vehicle. Note that the monitoring party, theadministrator, or the like may be inside the work vehicle, near the workvehicle, or far from the work vehicle.

The harvester 1 includes a satellite positioning module 80 that outputspositioning data on the basis of a GPS signal from an artificialsatellite GS used in GPS (global positioning systems). The harvester 1has a function for calculating a host vehicle position, which ispositional coordinates of a specific part of the harvester 1, from thepositioning data. The harvester 1 has an autonomous travel function thatautomates the traveling harvest work by steering so as to follow atravel route which takes a calculated host vehicle position as anobjective. When unloading harvested crops that have been harvested whiletraveling, it is necessary for the harvester 1 to approach the vicinityof a transport vehicle CV, which itself is parked near the ridge, andpark. When the parking position of the transport vehicle CV isdetermined in advance, this kind of approaching travel, i.e.,temporarily deviating from the work travel in the area CA to be workedand then returning to the work travel, can also be achieved throughautonomous travel. Travel routes for departing the area CA to be workedand returning to the area CA to be worked are generated at the point intime when the outer peripheral area SA is set. Note that a refuelingvehicle or another work support vehicle can be parked instead of thetransport vehicle CV.

Basic Flow of Work Vehicle Automatic Traveling System

For the harvester 1 incorporated into the work vehicle automatictraveling system according to the present invention to carry out theharvesting work through autonomous travel, it is necessary to provide atravel route managing device that generates travel routes serving asobjectives of the travel and manages those travel routes. The basicconfiguration of this travel route managing device, and a basic flow ofautonomous travel control using the travel route managing device, willbe described using FIG. 2.

Having arrived at the field, the harvester 1 harvests a crop whilecircling the inner sides of the border lines of the field. This work iscalled circular harvesting and is well-known as harvesting work. At thistime, forward and reverse travel is repeated in corner areas to ensurethat no unreaped grain remains. This embodiment assumes that at leastthe outermost pass is made manually so that nothing is left unreaped andthe vehicle does not collide with the ridge. The remaining interiorpasses may be carried out through autonomous travel using an autonomoustravel program specifically for circular harvesting, or the manualtravel may be continued after the circular harvesting in the outermostpass. As the shape of the area CA to be worked that remains on the innerside of the trajectory of this circling travel, a polygon that is assimple as possible, and preferably a quadrangle, is employed tofavorably accommodate the autonomous work travel. A circling routeelement for traveling around the outer peripheral area SA is created onthe basis of travel trajectory position data obtained from the circularharvesting on the inner side.

Furthermore, the trajectory of this circling travel can be obtained onthe basis of a host vehicle position calculated by a host vehicleposition calculating unit 53 from the positioning data of the satellitepositioning module 80. Furthermore, outer shape data of the field, andparticularly outer shape data of the area CA to be worked, which is theunharvested area located on the inner side of the circling traveltrajectory, is generated by an outer shape data generating unit 43 onthe basis of the travel trajectory. The field is managed by an areasetting unit 44, as the outer peripheral area SA and the area CA to beworked, separately.

The work travel in the area CA to be worked is carried out throughautonomous travel. As such, a travel route element set, which is atravel route for travel covering the area CA to be worked (travel thatcompletely covers the work width), is managed by a route managing unit60. This travel route element set is an aggregate of many travel routeelements. The route managing unit 60 calculates the travel route elementset on the basis of the outer shape data of the area CA to be worked,and stores the set in memory in a readable format.

In this work vehicle automatic traveling system, an overall travel routeis not determined in advance before the work travel in the area CA to beworked. Rather, the travel route can be changed midway through travel inaccordance with circumstances such as the work environment of the workvehicle. To that end, a work state evaluating unit 55 that evaluates thestate of the harvester 1, the state of the work site, commands from themonitoring party, and so on, and outputs state information, is provided.Note that the minimum unit (link) between a point (node) and a point(node) where the travel route can be changed is a travel route element.When the autonomous travel is started from a specified location, a nexttravel route element, which is to be traveled next, is selected insequence from the travel route element set by a route element selectingunit 63. An autonomous travel controlling unit 511 generates autonomoustravel data on the basis of the selected travel route element and thehost vehicle position, so that the vehicle follows that travel routeelement, and executes the autonomous travel.

In FIG. 2, a travel route generating device that generates the travelroutes for the harvester 1 is constituted by the outer shape datagenerating unit 43, the area setting unit 44, and the route managingunit 60. The travel route determination device that determines thetravel routes for the harvester 1 is constituted by the host vehicleposition calculating unit 53, the area setting unit 44, the routemanaging unit 60, and the route element selecting unit 63. The travelroute generating device, the travel route determination device, and thelike can be incorporated into a control system of the harvester 1, whichis capable of conventional autonomous travel. Alternatively, the travelroute generating device, the travel route determination device, and soon can be configured in a computer terminal, and the autonomous travelcan be realized by connecting that computer terminal to the controlsystem of the harvester 1 so as to be capable of exchanging data.

When a plurality of the harvesters 1, which carry out work travelcooperatively, are incorporated into the work vehicle automatictraveling system, an other vehicle positional relationship calculatingunit 56, which calculates the positional relationship between theharvesters 1, is included. The other vehicle positional relationshipcalculating unit 56 calculates the other vehicle positionalrelationship, which includes the position of the one harvester 1 (thehost vehicle position), the position of the other harvester 1 (an othervehicle position), the travel direction of the one harvester 1, thetravel direction of the other harvester 1, and the like. The othervehicle positional relationship is one piece of data expressing the worktravel states of the harvesters 1. The work travel state is stateinformation output from the work state evaluating unit 55 by evaluatingthe states of the harvesters 1, the state of the work site, commandsfrom the monitoring party, and so on. As illustrated in FIG. 2, theother vehicle positional relationship calculated by the other vehiclepositional relationship calculating unit 56 is sent to the work stateevaluating unit 55. When a plurality of harvesters carry out work travelcooperatively, the work state evaluating unit 55 sends the work travelstate of the other vehicle to the route element selecting unit 63.

Overview of Travel Route Element Set

As an example of the travel route element set, FIG. 3 illustrates atravel route element set in which multiple parallel dividing lines thatdivide the area CA to be worked into rectangular shapes serve as travelroute elements. This travel route element set has straight line-shapedtravel route elements, each element having two nodes (points on bothends; called “route changeable points”, where the route can be changed,here) connected by a single link, with the elements being arranged inparallel. The travel route elements are set to be arranged at equalintervals by adjusting the overlap amount of work width. U-turn travel(e.g., travel that switches the direction by 180°) is carried out inorder to move from an endpoint of a travel route element represented byone straight line to an endpoint of a travel route element representedby another straight line. Autonomous travel that connects such paralleltravel route elements through U-turn travel will be called “linearback-and-forth travel” hereinafter. This U-turn travel includes normalU-turn travel and switchback turn travel. The normal U-turn travel iscarried out only when the harvester 1 is moving forward, and thetrajectory of that travel has a U shape. Switchback turn travel iscarried out using both forward and reverse travel of the harvester 1,and although the trajectory of the travel is not a U shape, theharvester 1 ultimately switches the travel to the same direction as thatachieved by the normal U-turn travel. The normal U-turn travel requiresa distance that encloses two or more travel route elements between theroute changeable point before switching the direction of travel and theroute changeable point after switching the direction of travel. Forshorter distances, switchback turn travel is used. In other words,unlike normal U-turn travel, switchback turn travel is carried out inreverse as well, which means that the turn radius of the harvester 1 hasless of an effect, and there are more options for travel route elementsto move to. However, because switchback turn travel involves switches inthe forward and reverse directions, switchback turn travel generallytakes more time than normal U-turn travel.

As another example of a travel route element set, FIG. 4 illustrates atravel route element set constituted by multiple mesh lines extending inthe vertical and horizontal directions (corresponding to “mesh lines”according to the present invention) that divide the area CA to be workedinto a mesh. Routes can be changed at points where mesh lines intersect(route changeable points) and both endpoints of the mesh lines (routechangeable points). In other words, this travel route element setconstructs a route network where the points of intersection and the endpoints of the mesh lines function as nodes and the sides of each meshsegmented by the mesh lines function as links, enabling travel having ahigh level of freedom. In addition to the above-described linearback-and-forth travel, “spiral travel” moving from the outside to theinside as indicated in FIG. 4, “zigzag travel”, and so on, for example,are also possible. Furthermore, it is also possible to change fromspiral travel to linear back-and-forth travel midway through work. Notethat a circling route element set, which is an aggregate of circlingroute elements, create the travel route for traveling around the outerperipheral area SA.

Concepts When Selecting Travel Route Element

Selection rules used when the route element selecting unit 63 selectsthe next travel route element, which is the next travel route element tobe traveled in sequence, can be divided into static rules, which are setin advance before work travel, and dynamic rules, which are used in realtime during work travel. The static rules include rules for selectingtravel route elements on the basis of a predetermined basic travelpattern, e.g., selecting travel route elements so as to achieve linearback-and-forth travel while carrying out U-turn travel as illustrated inFIG. 3, rules for selecting travel route elements so as to achievecounterclockwise spiral travel moving from the outside to the inside asillustrated in FIG. 4, and so on. In principle, dynamic rules are usedpreferentially over static rules. The dynamic rules include the contentof the state information, such as the state of the harvester 1, thestate of the work site, commands from a monitoring party (including adriver, an administrator, and so on), and the like, which change in realtime. The work state evaluating unit 55 takes various types of primaryinformation (the work environment), the states of the harvesters 1, thestate of the work site, commands from the monitoring party, and the likeas input parameters, and outputs the state information. This primaryinformation includes not only signals from various sensors and switchesprovided in the harvester 1, but also weather information, timeinformation, external facility information from drying facilities or thelike, and so on. Furthermore, when a plurality of harvesters 1 workcooperatively, the state information output from the work stateevaluating unit 55 also includes the other vehicle positionalrelationship calculated by the other vehicle positional relationshipcalculating unit 56. This state information is used as the work travelstate of the other vehicle.

Furthermore, the route element selecting unit 63 includes a cooperativeroute element selection rule, which is employed when a plurality ofharvesters 1 carry out work travel cooperatively in the area CA to beworked, and an independent route element selection rule, which isemployed when a single harvester 1 carries out work travel independentlyin the area CA to be worked. When a single harvester 1 carries out worktravel independently in the area CA to be worked, and a differentharvester 1 is carrying out circling travel based on the circling routeelement or is stopped, the route element selecting unit 63 of the singleharvester 1 selects the next travel route element on the basis of theindependent route element selection rule.

Overview of Harvester

FIG. 5 is a side view of the harvester 1 serving as the work vehicleemployed in the descriptions of this embodiment. The harvester 1includes a crawler-type vehicle body 11. A driving section 12 isprovided on a front part of the vehicle body 11. A threshing device 13and a harvested crop tank 14 that holds harvested crops are arranged inthe left-right direction to the rear of the driving section 12. Aharvesting section 15 is provided to the front of the vehicle body 11,with the height of the harvesting section 15 being adjustable. A reel 17that raises grain is provided to the front of the harvesting section 15,with the height of the reel 17 being adjustable. A transport device 16that transports the reaped grain is provided between the harvestingsection 15 and the threshing device 13. A discharge device 18 thatdischarges the harvested crops from the harvested crop tank 14 isprovided in an upper part of the harvester 1. A load sensor that detectsthe weight of the harvested crops (an accumulation state of theharvested crops) is installed in a low part of the harvested crop tank14, and a yield meter, a taste analyzer, and so on are installed withinand around the harvested crop tank 14. Measurement data includingmoisture values and protein values of the harvested crops are outputfrom the taste analyzer as quality data. The harvester 1 is providedwith the satellite positioning module 80, which is constituted by a GNSSmodule, a GPS module, or the like. A satellite antenna for receiving GPSsignals, GNSS signals, and so on is attached to an upper part of thevehicle body 11 as a constituent element of the satellite positioningmodule 80. Note that the satellite positioning module 80 can include aninertial navigation module incorporating a gyro accelerometer, amagnetic direction sensor, and so on in order to complement thesatellite navigation.

In FIG. 5, the monitoring party (including a driver, an administrator,and the like), which monitors the movement of the harvester 1, boardsthe harvester 1, and brings a communication terminal 4, which themonitoring party uses for operation, into the harvester 1. However, thecommunication terminal 4 may be attached to the harvester 1.Furthermore, the monitoring party and the communication terminal 4 maybe located outside the harvester 1.

The harvester 1 is capable of autonomous travel through autonomoussteering, and manual travel through manual steering. Conventionalautonomous travel, in which the overall travel route is determined inadvance, and autonomous travel in which the next travel route isdetermined in real time on the basis of state information, are possibleas the autonomous travel. In the present application, the former travel,in which the overall travel route is determined in advance, will becalled “traditional travel”, and the latter travel, in which the nexttravel route is determined in real time, will be called “autonomoustravel”, so as to handle the two as distinct concepts. The configurationis such that the routes of the traditional travel are registered inadvance according to several patterns, or can be set as desired by themonitoring party using the communication terminal 4 or the like, forexample.

Function Control Blocks for Autonomous Travel

FIG. 6 illustrates a control system constructed in the harvester 1, anda control system of the communication terminal 4. In this embodiment,the travel route managing device that manages travel routes for theharvester 1 is constituted by a first travel route managing module CM1constructed in the communication terminal 4, and a second travel routemanaging module CM2 constructed in a control unit 5 of the harvester 1.

The communication terminal 4 includes a communication control unit 40, atouch panel 41, and so on, and functions as a computer system, a userinterface function for inputting conditions required for autonomoustravel realized by the control unit 5, and so on. By using thecommunication control unit 40, the communication terminal 4 can exchangedata with a management computer 100 over a wireless connection or theInternet, and can also exchange data with the control unit 5 of theharvester 1 using a wireless LAN, a wired LAN, or another communicationmethod. The management computer 100 is a computer system installed in amanagement center KS in a remote location, and functions as a cloudcomputer. The management computer 100 stores information sent fromfarmers, agricultural associations, agriculture industry groups, and soon, and can also send information in response to requests. FIG. 6illustrates a work site information storage unit 101 and a work planmanaging unit 102 as units that realize such server functions. Thecommunication terminal 4 processes data on the basis of external dataobtained from the management computer 100, the control unit 5 of theharvester 1, and so on through the communication control unit 40, and onthe basis of input data such as user instructions (conditions necessaryfor autonomous travel) input through the touch panel 41. Results of thisdata processing are displayed in a display panel unit of the touch panel41, and can also be sent from the communication terminal 4 to themanagement computer 100, the control unit 5 of the harvester 1, and soon through the communication control unit 40.

Field information including a topographical map of the vicinity of thefield, attribute information of the field (exits and entries to thefield, the direction of rows, and so on), and the like is stored in thework site information storage unit 101. The work plan managing unit 102of the management computer 100 manages a work plan manual denoting thedetails of the work for a specified field. The field information and thework plan manual can be downloaded to the communication terminal 4, thecontrol unit 5 of the harvester 1, and so on in response to an operationby the monitoring party or program executed automatically. The work planmanual includes various types of information (work conditions)pertaining to the work for the field designated to be worked. Thefollowing can be given as examples of this information (workconditions).

(a) travel patterns (linear back-and-forth travel, spiral travel, zigzagtravel, and so on).

(b) the parking position of a support vehicle such as the transportvehicle CV, a parking position of the harvester 1 for unloadingharvested crops or the like, and so on.

(c) the work format (work by a single harvester 1, or work by multipleharvesters 1).

(d) a so-called middle dividing line.

(e) values for the vehicle speed, the rotation speed of the threshingdevice 13, and so on based on the type of crop to be harvested (rice(Japonica rice, Indica rice), wheat, soybeans, rapeseed, buckwheat, andthe like).

Settings for the travel device parameters, settings for the harvestingdevice parameters, and so on corresponding to the type of crop are sentautomatically on the basis of the information (e) in particular, whichavoids setting mistakes.

Note that the position where the harvester 1 parks in order to unloadharvested crops into the transport vehicle CV is a harvested cropunloading parking position, and the position where the harvester 1 parksin order to be refueled by a refueling vehicle is a refueling parkingposition. In this embodiment, these are set to substantially the sameposition.

The above-described information (a) to (e) may be input by themonitoring party through the communication terminal 4 serving as a userinterface. The communication terminal 4 is also provided with an inputfunction for instructing autonomous travel to start and stop, an inputfunction for indicating whether the work travel is autonomous travel ortraditional travel as described above, an input function for making fineadjustments to the values of parameters pertaining to a vehicle traveldevice group 71 including a travel speed variation device, a work devicegroup 72 including the harvesting section 15 (see FIG. 6), and so on.The height of the reel 17, the height of the harvesting section 15, andso on can be given as examples of the values of the parameters of thework device group 72 to which fine adjustments can be made.

The state of the communication terminal 4 can, through an artificialswitching operation, be switched to an animated display state indicatingautonomous travel routes or traditional travel routes, a state ofdisplaying the above-described parameters/fine adjustments, and so on.This animated display animates the travel trajectory of the harvester 1traveling along the autonomous travel routes or traditional travelroutes, which are travel routes in the autonomous travel or traditionaltravel in which the overall travel route has been determined in advance,and displays the animation in a display panel unit of the touch panel41. Using this animated display, the driver can intuitively confirm thetravel routes to be traveled on before the travel starts.

A work site data input unit 42 inputs the field information downloadedfrom the management computer 100, information obtained from the workplan manual or the communication terminal 4, or the like. A schematicdiagram of the field, the positions of exits from and entrances to thefield, a parking position for receiving support from a work supportvehicle, and so on included in the field information are displayed inthe touch panel 41. This makes it possible to assist the circling travelfor forming the outer peripheral area SA carried out by the driver. Ifdata such as the exits from and entrances to the field, the parkingposition, and so on is not included in the field information, the usercan input that information through the touch panel 41. The outer shapedata generating unit 43 calculates an accurate outer shape and outerdimensions of the field, and an outer shape and outer dimensions of thearea CA to be worked, from travel trajectory data obtained from thecontrol unit 5 when the harvester 1 carries out the circling travel(that is, time series data of the host vehicle position). The areasetting unit 44 sets the outer peripheral area SA and the area CA to beworked on the basis of the travel trajectory data from when theharvester 1 carries out the circling travel. Positional coordinates ofthe outer peripheral area SA and the area CA to be worked that have beenset, i.e., the outer shape data of the outer peripheral area SA and thearea CA to be worked, are used to generate the travel routes forautonomous travel. In this embodiment, the second travel route managingmodule CM2 constructed in the control unit 5 of the harvester 1generates the travel routes, and thus the positional coordinates of theouter peripheral area SA and the area CA to be worked that have been setare sent to the second travel route managing module CM2.

If the field is large, work is carried out to create a middle-dividedarea, which divides the field into multiple segments using travel routesthat intersect head-on. This work is called “middle dividing”. Themiddle dividing position can also be specified through a touch operationmade on a diagram of the outer shape of the work site displayed in thescreen of the touch panel 41. Of course, the setting of the middledividing position also affects the generation of the travel routeelement set for autonomous travel, and thus may be carried outautomatically when generating the travel route element set. At thattime, if the parking position of the harvester 1 for receiving supportfrom a work support vehicle such as the transport vehicle CV is locatedon a line extending from the middle-divided area, the travel forunloading the harvested crops from all segments is carried outefficiently.

The second travel route managing module CM2 includes the route managingunit 60, the route element selecting unit 63, and a route setting unit64. The route managing unit 60 calculates the travel route element setand the circling route element set and stores those sets so as to becapable of readout. The travel route element set is an aggregate ofmultiple travel route elements constituting a travel route covering thearea CA to be worked. The circling route element set is an aggregate ofcircling route elements constituting a circling route for travelingaround the outer peripheral area SA. The route managing unit 60 includesa mesh route element calculating unit 601, a rectangular route elementcalculating unit 602, and a U-turn route calculating unit 603 asfunction units for calculating the travel route element set. The routeelement selecting unit 63 selects the next travel route element, whichis to be traveled next, sequentially from the travel route element set,on the basis of various selection rules which will be described indetail later. The route setting unit 64 sets the selected next travelroute element as a target travel route for autonomous travel.

The mesh route element calculating unit 601 can calculate a travel routeelement set, which is a mesh line set (corresponding to a “mesh lineset” according to the present invention) constituted by mesh lines thatdivide the area CA to be worked into a mesh, and can also calculatepositional coordinates of points of intersection between and endpointsof the mesh lines. These travel route elements correspond to the targettravel route when the harvester 1 travels autonomously, and thus theharvester 1 can change the route from one travel route element toanother travel route element at the points of intersection between andthe endpoints of the mesh lines. In other words, the points ofintersection between and the endpoints of the mesh lines function as theroute changeable points that permit the harvester 1 to change its route.

FIG. 7 schematically illustrates the mapping of the mesh line set, whichis an example of the travel route element set, onto the area CA to beworked. Using the work width of the harvester 1 as a mesh interval, themesh route element calculating unit 601 calculates a travel routeelement set so as to completely cover the area CA to be worked with meshlines. As described above, the area CA to be worked as an area on theinner side of the outer peripheral area SA, which is formed by makingthree to four circular passes, at the work width, from the border of thefield toward the inside of the field. Accordingly, the area CA to beworked will basically have the same outer shape as the field. However,there are cases where the outer peripheral area SA is created so thatthe area CA to be worked is substantially polygonal, and preferablysubstantially quadrangular, to make it easier to calculate the meshlines. In FIG. 7, the shape of the area CA to be worked is a deformedquadrangle constituted by a first side S1, a second side S2, a thirdside S3, and a fourth side S4.

As illustrated in FIG. 7, the mesh route element calculating unit 601calculates a first straight line set, arranged on the area CA to beworked, from a position distanced from the first side S1 of the area CAto be worked by a distance equivalent to half the work width of theharvester 1, with the lines being parallel to the first side S1 andarranged at intervals equivalent to the work width of the harvester 1.Likewise, a second straight line set, arranged on the area CA to beworked, from a position distanced from the second side S2 by a distanceequivalent to half the work width of the harvester 1, with the linesbeing parallel to the second side S2 and arranged at intervalsequivalent to the work width of the harvester 1; a third straight lineset, arranged on the area CA to be worked, from a position distancedfrom the third side S3 by a distance equivalent to half the work widthof the harvester 1, with the lines being parallel to the third side S3and arranged at intervals equivalent to the work width of the harvester1; and a fourth straight line set, arranged on the area CA to be worked,from a position distanced from the fourth side S4 by a distanceequivalent to half the work width of the harvester 1, with the linesbeing parallel to the fourth side S4 and arranged at intervalsequivalent to the work width of the harvester 1, are calculated. In thismanner, the first side S1 to the fourth side S4 serve as reference linesfor generating the straight line sets serving as the travel routeelement set. If the positional coordinates of two points on a straightline are known, that straight line can be identified; thus each straightline serving as a travel route element is turned into data indicating astraight line defined by the positional coordinates of the two points onthat straight line, and is stored in memory in a predetermined dataformat. This data format includes a route number serving as a routeidentifier for identifying that travel route element, as well as a routetype, the side of the outer quadrangle serving as a reference, whetherthe element is untraveled/already traveled, and so on as attributevalues of the travel route element.

Of course, the above-described calculation of the straight line groupscan be applied to an area CA to be worked that is a polygon aside from aquadrangle. In other words, assuming the area CA to be worked is anN-cornered shape, where N is an integer of 3 or more, the travel routeelement set is constituted by N straight line sets, from a firststraight line set to an Nth straight line set. Each straight line setincludes straight lines arranged at predetermined intervals (the workwidth) parallel to one of the sides of the N-cornered shape.

Note that a travel route element set is set by the route managing unit60 in the outer peripheral area SA as well. The travel route element setin the outer peripheral area SA is used when the harvester 1 travels inthe outer peripheral area SA. The travel route element set in the outerperipheral area SA is given attribute values such as a departure route,a return route, an intermediate straight route for U-turn travel, and soon. “Departure route” refers to a travel route element set used for theharvester 1 to depart the area CA to be worked and enter the outerperipheral area SA. “Return route” refers to a travel route element setused for the harvester 1 to return from the outer peripheral area SA tothe work travel in the area CA to be worked. The intermediate straightroute for U-turn travel (referred to simply as an “intermediate straightroute” hereinafter) is a straight line-shaped route constituting part ofa U-turn travel route used during U-turn travel in the outer peripheralarea SA. In other words, the intermediate straight route is a straightline-shaped travel route element set constituting a straight line partconnecting a turning route at the start of U-turn travel with a turningroute at the end of U-turn travel, and is a route provided parallel toeach side of the area CA to be worked within the outer peripheral areaSA. In work travel that begins as spiral travel and then switches tolinear back-and-forth travel midway through, the unharvested area willbecome smaller than the area CA to be worked on all sides, depending onthe spiral travel. Accordingly, executing U-turn travel within the areaCA to be worked is better, in terms of making the work travel efficient,than expressly moving to the outer peripheral area SA. This eliminateswasteful travel and is efficient. Thus when executing U-turn travel inthe area CA to be worked, the intermediate straight route is movedinward in a parallel manner, in accordance with the position of theouter peripheral line of the unharvested area.

In FIG. 7, the shape of the area CA to be worked is a deformedquadrangle. As such, there are four sides serving as references forgenerating the mesh route element set. Here, if the area CA to be workedis a rectangle or a square, there are two sides serving as referencesfor generating the mesh route element set. In this case, the mesh routeelement set has a simpler structure.

In this embodiment, the route managing unit 60 is provided with therectangular route element calculating unit 602 as an optional travelroute element calculating unit. The travel route element set calculatedby the rectangular route element calculating unit 602 is, as illustratedin FIG. 3, a parallel straight line set (corresponding to a “parallelline set” according to the present invention) which extends parallel toa reference side, e.g., the longest side, selected from the sidesconstituting the outer shape of the area CA to be worked, and whichcovers the area CA to be worked with the work width (completely coverswith the work width). The travel route element set calculated by therectangular route element calculating unit 602 divides the area CA to beworked into rectangular shapes. Furthermore, the travel route elementset is an aggregate of parallel straight lines sequentially connected byU-turn travel routes over which the harvester 1 executes U-turn travel(corresponding to “parallel lines” according to the present invention).In other words, if the travel over one travel route element that is aparallel straight line ends, the U-turn route calculating unit 603determines the U-turn travel route for moving to the next selectedtravel route element.

The U-turn route calculating unit 603 calculates the U-turn travel routefor connecting two travel route elements, which have been selected fromthe travel route element set calculated by the rectangular route elementcalculating unit 602, using U-turn travel. Once the outer peripheralarea SA and so on have been set, the U-turn route calculating unit 603calculates a single intermediate straight route parallel to the outerperipheral side of the area CA to be worked, for each area of the outerperipheral area SA corresponding to outer peripheral sides (outer sides)of the area CA to be worked, on the basis of the outer shape and outerdimensions of the outer peripheral area SA, the outer shape and outerdimensions of the area CA to be worked, the turn radius of the harvester1, and so on. Additionally, when normal U-turn travel and switchbackturn travel are executed, the U-turn route calculating unit 603calculates a start-side turning route connecting the travel routeelement currently traveled and the corresponding intermediate straightroute, and an end-side turning route connecting the correspondingintermediate straight route and the destination travel route element.The principles of generating the U-turn travel route will be describedlater.

As illustrated in FIG. 6, the control unit 5 of the harvester 1, whichconstitutes the second travel route managing module CM2, is providedwith various functions for executing work travel. The control unit 5 isconfigured as a computer system, and is provided with an outputprocessing unit 7, an input processing unit 8, and a communicationprocessing unit 70, as an input/output interface. The output processingunit 7 is connected to a vehicle travel device group 71, the work devicegroup 72, a notifying device 73, and so on provided in the harvester 1.The vehicle travel device group 71 includes devices that are controlledso that the vehicle can travel, such as a steering device for adjustingthe speed of left and right crawlers of the vehicle body 11 to executesteering, as well as a shifting mechanism, an engine unit, and so on(not shown). The work device group 72 includes devices constituting theharvesting section 15, the threshing device 13, the discharge device 18,and so on. The notifying device 73 includes a display, a lamp, aspeaker, and the like. The outer shape of the field, as well as varioustypes of notification information such as already-traveled travel routes(travel trajectories) and travel routes to be traveled next, aredisplayed in the display in particular. The lamp and speaker are used tonotify the occupant (driver or monitoring party) of caution informationor warning information such as travel caution items, deviation fromtarget travel routes during autonomously-steered travel, and so on.

The communication processing unit 70 has a function for receiving dataprocessed by the communication terminal 4, as well as sending dataprocessed by the control unit 5. Accordingly, the communication terminal4 can function as a user interface of the control unit 5. Thecommunication processing unit 70 is furthermore used for exchanging datawith the management computer 100, and thus has a function for handling avariety of communication formats.

The input processing unit 8 is connected to the satellite positioningmodule 80, a travel system detection sensor group 81, a work systemdetection sensor group 82, an automatic/manual toggle operationimplement 83, and so on. The travel system detection sensor group 81includes sensors that detect travel states, such as engine RPM, a shiftstate, and so on. The work system detection sensor group 82 includes asensor that detects a height position of the harvesting section 15, asensor that detects an amount held in the harvested crop tank 14, and soon. The automatic/manual toggle operation implement 83 is a switch thatselects either an autonomous travel mode, which travels with autonomoussteering, or a manual travel mode, which travels with manual steering.Additionally, a switch for switching between autonomous travel andtraditional travel is provided in the driving section 12, or configuredin the communication terminal 4.

Furthermore, the control unit 5 is provided with a travel control unit51, a work control unit 52, the host vehicle position calculating unit53, a notification unit 54, the work state evaluating unit 55, and theother vehicle positional relationship calculating unit 56. The hostvehicle position calculating unit 53 calculates the host vehicleposition on the basis of positioning data output from the satellitepositioning module 80. Because the harvester 1 is configured to becapable of traveling through both autonomous travel (autonomoussteering) and manual travel (manual steering), the travel control unit51 that controls the vehicle travel device group 71 includes theautonomous travel controlling unit 511 and a manual travel controllingunit 512. The manual travel controlling unit 512 controls the vehicletravel device group 71 on the basis of operations made by the driver.The autonomous travel controlling unit 511 calculates directional skewand positional skew between the travel route set by the route settingunit 64 and the host vehicle position, generates autonomous steeringcommands, and outputs the commands to the steering device via the outputprocessing unit 7. The work control unit 52 supplies control signals tothe work device group 72 in order to control the operations of operationdevices provided in the harvesting section 15, the threshing device 13,the discharge device 18, and so on that constitute the harvester 1. Thenotification unit 54 generates notification signals (display data, audiodata, and so on) for notifying the driver, the monitoring party, or thelike of necessary information through the notifying device 73, which isa display or the like. The work state evaluating unit 55 outputs thestate information, which includes the states of the harvesters 1, thestate of the work site, and commands from people (the monitoring party,a driver, an administrator, and the like), from the detection resultsfrom various types of sensors, operation results from various types ofoperational implements, and so on. If a plurality of harvesters 1 areworking cooperatively, the other vehicle positional relationshipcalculating unit 56 calculates the other vehicle positionalrelationship, indicating the position of the other vehicle and thepositional relationship between the host vehicle and the other vehicle.The host vehicle position and travel route elements selected by the hostvehicle, and the other vehicle position and travel route elementsselected by the other vehicle, are used in the calculation of the othervehicle positional relationship. Furthermore, the other vehiclepositional relationship calculating unit 56 has a function forcalculating an estimated contact position between the work vehicles.

In addition to controlling the steering, the autonomous travelcontrolling unit 511 can also control the vehicle speed. As describedabove, the vehicle speed is set through the communication terminal 4 byan occupant, for example, before work is started. The vehicle speedsthat can be set include a vehicle speed used during travel forharvesting, a vehicle speed used during turning when not harvesting(U-turn travel and the like), a vehicle speed used when departing thearea CA to be worked and traveling the outer peripheral area SA whenunloading harvested crops or refueling, and so on. The autonomous travelcontrolling unit 511 calculates an actual vehicle speed on the basis ofthe positioning data obtained by the satellite positioning module 80.The output processing unit 7 sends, to the vehicle travel device group71, speed change operation commands or the like for the travel speedvariation device so that the actual vehicle speed matches the setvehicle speed.

Autonomous Travel Routes

As examples of autonomous travel in the work vehicle automatic travelingsystem, an example of linear back-and-forth travel, and an example ofspiral travel will be described separately.

First, an example of linear back-and-forth travel using the travel routeelement set calculated by the rectangular route element calculating unit602 will be described. FIG. 8 schematically illustrates a travel routeelement set constituted by 21 travel route elements expressed asrectangles with a shortened linear length, where route numbers areprovided above each travel route element. The harvester 1 is positionedat the 14th travel route element when the work travel is started. Thedegrees of separation between the travel route element where theharvester 1 is positioned and the other travel route elements areindicated by the positive or negative integers provided below each ofthe routes. In FIG. 8, a priority level at which the harvester 1positioned at the 14th travel route element is to move to the nexttravel route element is indicated by an integer value in the bottom partof each travel route element. A lower value indicates a higher prioritylevel, and is selected preferentially. When moving from a travel routeelement for which travel has been completed to the next travel routeelement, the harvester 1 can execute normal U-turn travel, which isindicated in FIG. 9, or switchback turn travel. Here, normal U-turntravel is travel for moving to the next travel route element past atleast two travel route elements. Switchback turn travel, on the otherhand, is travel that enables movement passing less than two travel routeelements, i.e., movement to an adjacent travel route element. In normalU-turn travel, the harvester 1 switches directions by approximately 180°upon entering the outer peripheral area SA from the endpoint of thetravel route element being traveled, and enters an endpoint of thedestination travel route element. If there is a large gap between thetravel route element being traveled and the destination travel routeelement, the harvester 1 makes a turn of approximately 90°, continuesstraight for a corresponding distance, and then makes anotherapproximately 90° turn. In other words, normal U-turn travel is executedusing forward travel only. On the other hand, in switchback turn travel,when entering the outer peripheral area SA from an endpoint of thetravel route element being traveled, the harvester 1 first turnsapproximately 90°, reverses to a position for entering into thedestination travel route element smoothly using an approximately 90°turn, and then proceeds toward the endpoint of the destination travelroute element. Although this does complicate the steering control, italso makes it possible to move to a travel route element only a shortinterval away.

The selection of the next travel route element to be traveled is made bythe route element selecting unit 63. In this embodiment, basic prioritylevels for selecting the travel route element is set. In these basicpriority levels, the priority level of a properly-distanced travel routeelement is set to be the highest. The “properly-distanced travel routeelement” is a travel route element separated by a predetermined distancefrom the previous travel route element in the order. The priority levelis set to be lower for travel route elements further from the previoustravel route element in the order than the properly-distanced travelroute element. For example, when moving to the next travel routeelement, normal U-turn travel, which has a short travel distance, alsohas a short travel time and is therefore efficient. Accordingly, thepriority level is set to the highest level (priority level=1) for thetravel route elements that skip two spaces to the left and right. Travelroute elements that from the perspective of the harvester 1 are locatedfurther than the stated travel route elements have longer normal U-turntravel times as the distance from the harvester 1 increases.Accordingly, the priority level is set to be lower (priority level=2, 3,. . . ) as the distance from the harvester 1 increases. In other words,the numerical value of the priority level indicates an order ofpriority. However, when moving to a travel route element that skipseight spaces, normal U-turn travel has a longer travel time and is lessefficient than switchback turn travel. Accordingly, the priority levelfor movement to a travel route element that skips eight spaces is lowerthan that for switchback turn travel. In switchback turn travel, thepriority level for moving to a travel route element that skips one spaceis higher than the priority level for moving to the adjacent travelroute element. This is because switchback turn travel to an adjacenttravel route element requires sharp steering, which is likely to damagethe field. Although the movement to the next travel route element can bemade in either the left or right direction, a rule that prioritizesmovement to a travel route element to the left or movement to a travelroute element to the right is employed in accordance with conventionalwork customs. Thus in the example illustrated in FIG. 8, the harvester 1located at route number 14 selects the travel route element having aroute number of 17 as the travel route element to be traveled to next.The priority level setting is carried out when the harvester 1 enters anew travel route element.

A travel route element that has already been selected, i.e., a travelroute element for which work has been completed is, as a rule,prohibited from being selected. Thus as illustrated in FIG. 10, if, forexample, route number 11 or route number 17, which have priority levelsof 1, are already-worked sites (already-harvested sites), the harvester1 located at route number 14 selects the travel route element having aroute number of 18, which has a priority level of 2, as the travel routeelement to be traveled next.

FIG. 11 illustrates an example of spiral travel using travel routeelements calculated by the mesh route element calculating unit 601. Theouter peripheral area SA and the area CA to be worked in the fieldillustrated in FIG. 11 are the same as those illustrated in FIG. 7, asis the travel route element set that has been set for the area CA to beworked. Here, for descriptive purposes, travel route elements taking thefirst side S1 as a reference line are indicated by L11, L12, and so on,travel route elements taking the second side S2 as a reference line areindicated by L21, L22, and so on, travel route elements taking the thirdside S3 as a reference line are indicated by L31, L32, and so on, andtravel route elements taking the fourth side S4 as a reference line areindicated by L41, L42, and so on.

The bold lines in FIG. 11 represent a spiral-shaped travel routetraveled by the harvester 1 from the outside toward the inside. Thetravel route element L11, which is located in the outermost pass of thearea CA to be worked, is selected as the first travel route. A routechange of substantially 90° is made at the point of intersection betweenthe travel route element L11 and the travel route element L21, afterwhich the harvester 1 travels on the travel route element L21.Furthermore, a route change of substantially 70° is made at the point ofintersection between the travel route element L21 and the travel routeelement L31, after which the harvester 1 travels on the travel routeelement L31. A route change of substantially 110° is made at the pointof intersection between the travel route element L31 and the travelroute element L41, after which the harvester 1 travels on the travelroute element L41. Next, the harvester 1 moves to the travel routeelement L12 on the inside of the travel route element L11 at the pointof intersection between the travel route element L12 and the travelroute element L41. By repeating such travel route element selection, theharvester 1 executes work travel in a spiral shape, moving from theoutside to the inside of the area CA to be worked in the field. Thuswhen a spiral travel pattern is set, the harvester 1 switches directionsby making route changes at the points of intersection between travelroute elements that both have an untraveled attribute and are located inthe outermost pass of the area CA to be worked.

FIG. 12 illustrates an example of U-turn travel using the same travelroute element set as that illustrated in FIG. 11. First, the travelroute element L11, which is located in the outer pass of the area CA tobe worked, is selected as the first travel route. The harvester 1 passesa following end (endpoint) of the travel route element L11, enters theouter peripheral area SA, makes a 90° turn so as to follow the secondside S2, and furthermore makes another 90° turn so as to enter a leadingend (endpoint) of the travel route element L14 extending parallel to thetravel route element L11. As a result, the harvester 1 moves from thetravel route element L11 to the travel route element L14 having skippedtwo travel route elements, through normal U-turn travel of 180°.Furthermore, after traveling the travel route element L14 and enteringthe outer peripheral area SA, the harvester 1 executes normal U-turntravel of 180°, and then moves to the travel route element L17 extendingparallel to the travel route element L14. In this matter, the harvester1 moves from the travel route element L17 to a travel route elementL110, and furthermore from the travel route element L110 to the travelroute element L16, ultimately completing the work travel for the entirearea CA to be worked in the field. As is clear from the foregoingdescriptions, the example of linear back-and-forth travel using thetravel route element set from the rectangular route element calculatingunit 602, which has been described using FIGS. 8, 9, and 10, can also beapplied to the linear back-and-forth travel using the travel routeelements calculated by the mesh route element calculating unit 601.

Accordingly, linear back-and-forth travel can be achieved using a travelroute element set that divides the area CA to be worked into rectangularshapes, as well as using a travel route element set that divides thearea CA to be worked into a mesh shape. To rephrase, a travel routeelement set that divides the area CA to be worked into a mesh shape canbe used in linear back-and-forth travel, spiral travel, and zigzagtravel, and furthermore, the travel pattern can be changed from spiraltravel to linear back-and-forth travel midway through the work.

Principle of Generating U-Turn Travel Route

A basic principle by which the U-turn route calculating unit 603generates a U-turn travel route will be described using FIG. 13. FIG. 13illustrates a U-turn travel route in which the harvester 1 moves from atravel route element corresponding to the start of the turn, indicatedby LS0, to a travel route element indicating the destination of theturn, indicated by LS1. In normal travel, if LS0 is a travel routeelement in the area CA to be worked, LS1 is typically a travel routeelement in the outer peripheral area SA (an intermediate straightroute), whereas if LS1 is a travel route element in the area CA to beworked, LS0 is typically a travel route element in the outer peripheralarea SA (an intermediate straight route). A linear equation (or twopoints on the straight lines) for the travel route elements LS0 and LS1are recorded in memory, and the point of intersection between the two(indicated by PX in FIG. 13) and an angle of intersection (indicated by0 in FIG. 13) are calculated from that linear equation. Next, aninscribed circle contacting both the travel route element LS0 and thetravel route element LS1, and having a radius equivalent to the minimumturn radius of the harvester 1 (indicated by r in FIG. 13), iscalculated. An arc (part of the inscribed circle) connecting the pointsof contact between the travel route elements LS0 and LS1 with theinscribed circle (indicated by PS0 and PS1 in FIG. 13) corresponds tothe turning route. Accordingly, a distance Y to a point of contactbetween the intersection point PX of the travel route elements LS0 andLS1, and the points of contact, is given by:Y=r/(tan(θ/2))Because the minimum turn radius is substantially set by thespecifications of the harvester 1, r is a control value. Note that rneed not be the same value as the minimum turn radius. A less extremeturn radius may be set in advance by the communication terminal 4 or thelike, and the turn operation may be programmed so as to follow that turnradius. In terms of travel control, the harvester 1 starts the turningtravel when the positional coordinates (PS0) where the distance to thepoint of intersection is Y are reached while traveling the travel routeelement LS0 where the turn starts; next, the turning travel ends when adifference between the direction of the harvester 1 during turningtravel and the direction of the travel route element LS1 serving as theturn destination falls within a permissible value. At this time, theturn radius of the harvester 1 need not perfectly match the radius r.Controlling the steering on the basis of the distance and directionaldifference from the travel route element LS1 serving as the turndestination makes it possible for the harvester 1 to move to the travelroute element LS1 serving as the turn destination.

FIGS. 14, 15, and 16 illustrate three specific examples of U-turntravel. In FIG. 14, the travel route element LS0 where the turn isstarted and the travel route element LS1 serving as the turn destinationextend at an angle from an outer side of the area CA to be worked, butmay extend perpendicular as well. Here, the U-turn travel route in theouter peripheral area SA is constituted by lines extending from thetravel route element LS0 and the travel route element LS1 into the outerperipheral area SA, an intermediate straight route corresponding to part(a line segment) of the travel route element in the outer peripheralarea SA, and two arc-shaped turning routes. This U-turn travel route canalso be generated according to the basic principle described using FIG.13. An angle of intersection θ1 and a point of intersection PX1 betweenthe intermediate straight route and the travel route element LS0 wherethe turn is started, and an angle of intersection θ2 and a point ofintersection PX2 between the intermediate straight route and the travelroute element LS1 serving as the destination of the turn, arecalculated. Furthermore, the positional coordinates of contact pointsPS10 and PS11 where the inscribed circle having the radius r (=the turnradius of the harvester 1) makes contact with the travel route elementLS0 where the turn is started and the intermediate straight route, andthe positional coordinates of contact points PS20 and PS21 where theinscribed circle having the radius r makes contact with the intermediatestraight route and the travel route element LS1 serving as thedestination of the turn, are calculated as well. The harvester 1 beginsthe turns at the contact points PS10 and PS20. Likewise, a U-turn travelroute for an area CA to be worked, which has been formed protruding in atriangular shape as indicated in FIG. 15, that skirts around thatprotruding triangular shape, can be generated in the same manner. Thepoints of intersection between the travel route elements LS0 and LS1 andtwo intermediate straight routes corresponding to parts (line segments)of the travel route element in the outer peripheral area SA are found.The basic principle described using FIG. 13 is applied in thecalculation of those points of intersection.

FIG. 16 illustrates turning travel achieved through switchback turntravel, where the harvester 1 moves from the travel route element LS0where the turn is started to the travel route element LS1 serving as thedestination of the turn. In this switchback turn travel, an inscribedcircle having the radius r, which makes contact with an intermediatestraight route that is a part (a line segment) of the travel routeelement in the outer peripheral area SA and that is parallel to an outerside of the area CA to be worked, and also makes contact with the travelroute element LS0, is calculated. Additionally, an inscribed circlehaving the radius r, which makes contact with the stated intermediatestraight route and the travel route element LS1, is also calculated. Inaccordance with the basic principle described using FIG. 13, thepositional coordinates of the points of contact between the twoinscribed circles and the intermediate straight route, the positionalcoordinates of the points of contact between the travel route elementLS0 where the turn is started and the inscribed circle, and thepositional coordinates of the point of contact between the travel routeelement LS1 serving as the destination of the turn and the inscribedcircle are calculated. The U-turn travel route for switchback turntravel is generated as a result. Note that the harvester 1 travels inreverse in the intermediate straight route in this switchback turntravel.

Travel for Switching Directions in Spiral Travel

FIG. 17 illustrates an example of travel for switching directions, usedfor changing the route at a point of intersection corresponding to theroute changeable point of the travel route element, in theabove-described spiral travel. This travel for switching directions willbe referred to as α-turn travel hereinafter. The travel route (α-turntravel route) in this α-turn travel is one kind of a so-called countertravel route, and is a route extending from the point of intersectionbetween the travel route element where the travel starts (indicated byLS0 in FIG. 17) and the travel route element serving as the destinationof the turn (indicated by LS1 in FIG. 17), passing forward through aturning route, and making contact with a travel route element serving asthe destination of the turn through a turning route in reverse. Theα-turn travel route is standardized, and thus the α-turn travel routegenerated in accordance with the angle of intersection between thetravel route element where the travel starts and the travel routeelement serving as the destination of the turn is registered in advance.Accordingly, the route managing unit 60 reads out the proper α-turntravel route on the basis of the calculated angle of intersection, andprovides the route setting unit 64 with the α-turn travel route.However, a configuration in which an automatic control program isregistered in the autonomous travel controlling unit 511 for each angleof intersection, and the autonomous travel controlling unit 511 readsout the proper automatic control program on the basis of the angle ofintersection calculated by the route managing unit 60, may be employedinstead of this configuration.

Route Selection Rules

The route element selecting unit 63 sequentially selects the travelroute elements on the basis of travel patterns input manually from awork plan manual received from the management center KS or from thecommunication terminal 4 (e.g., a linear back-and-forth travel patternor a spiral travel pattern), the host vehicle position, and the stateinformation output from the work state evaluating unit 55. In otherwords, unlike a case where the overall travel route is formed in advanceon the basis of a set travel pattern alone, a more appropriate travelroute is formed, which handles circumstances that cannot be predictedbefore the work. In addition to the above-described basic rules, theroute element selecting unit 63 has route selection rules A1 to A12,such as those described below, registered in advance, and theappropriate route selection rule is applied in accordance with thetravel pattern and the state information.

(A1) When the monitoring party (occupant) has made an operationrequesting a switch from autonomous travel to manual travel, theselection of travel route elements by the route element selecting unit63 is stopped after preparations for manual travel are complete. Suchoperations include operating the automatic/manual toggle operationimplement 83, operating a braking implement (and making a sudden stop inparticular), steering by greater than or equal to a predeterminedsteering angle using a steering implement (a steering lever or thelike), and so on. Furthermore, if the travel system detection sensorgroup 81 includes a sensor that detects the absence of the monitoringparty required to be present during autonomous travel, e.g., a weightdetection sensor provided in a seat or a seatbelt fastening detectionsensor, the autonomous travel control can be stopped on the basis of asignal from that sensor. In other words, when it is detected that themonitoring party is absent, the start of the autonomous travel control,or the travel of the harvester 1 itself, is stopped. Additionally, aconfiguration may be employed in which a fine adjustment is made to thetravel direction rather than stopping the autonomous travel control whenthe steering implement is operated at a steering angle that is extremelysmall and is smaller than the predetermined steering angle.

(A2) The autonomous travel controlling unit 511 monitors a relationship(distance) between an outer line position of the field and the hostvehicle position based on the positioning data. Then, the autonomoustravel controlling unit 511 controls the autonomous travel so as toavoid contact between the ridge and the vehicle when turning in theouter peripheral area SA. Specifically, the autonomous travel is stoppedand the harvester 1 is stopped, the type of turning travel is changed(changed from normal U-turn travel to switchback turn travel or α-turntravel), a travel route that does not pass through that area is set, orthe like. A configuration in which a warning such as “caution, narrowturning area” is provided may also be employed.

(A3) When the harvested crop tank 14 is full or almost full of harvestedcrops, and it is necessary to unload the harvested crops, an unloadrequest (a type of request for deviating from the work travel in thearea CA to be worked), which is one type of state information, is issuedfrom the work state evaluating unit 55 to the route element selectingunit 63. In this case, appropriate travel route elements (e.g., travelroute elements providing the shortest possible route) for deviating fromthe work travel in the area CA to be worked and traveling toward theparking position through the outer peripheral area SA are selected fromelements in the travel route element set for the outer peripheral areaSA that have a departure route attribute value, and elements in thetravel route element set for the area CA to be worked, on the basis ofthe parking position for unloading to the transport vehicle CV at theridge and the host vehicle position.

(A4) If the remaining fuel in the fuel tank is determined to be low onthe basis of a remaining fuel value calculated from a signal from aremaining fuel sensor and the like, a refueling request (a type ofdeparture request) is made. As with (A3), appropriate travel routeelements leading to a refueling position (e.g., travel route elementsproviding the shortest possible route) are selected on the basis of aparking position corresponding to a pre-set refueling position and thehost vehicle position.

(A5) When deviating from work travel in the area CA to be worked andentering the outer peripheral area SA, it is necessary to once againreturn to the area CA to be worked. As a travel route element serving asa starting point for returning to the area CA to be worked, the travelroute element closest to the point of departure, or the travel routeelement closest to the current position in the outer peripheral area SA,is selected from elements in the travel route element set for the outerperipheral area SA that have a return route attribute value, andelements in the travel route element set for the area CA to be worked.

(A6) When deviating from work travel in the area CA to be worked inorder to unload harvested crops or refuel, and then determining a travelroute for returning to the area CA to be worked, a travel route elementin the area CA to be worked that has already been worked (alreadytraveled) and has thus been given a “travel prohibited” attribute isrestored as a travel route element that can be traveled. When selectingan already-worked travel route element makes it possible to save apredetermined amount of time or more, that travel route element isselected. Furthermore, reverse travel can be used for the travel in thearea CA to be worked when departing from the area CA to be worked.

(A7) The timing for deviating from work travel in the area CA to beworked in order to unload harvested crops or refuel is determined on thebasis of the margin thereof, and the travel time or travel distance tothe parking position. In terms of unloading harvested crops, the marginis the predicted travel time or travel distance until the harvested croptank 14 becomes full from the current amount being held. In terms ofrefueling, the margin is the predicted travel time or travel distanceuntil the fuel in the fuel tank is completely exhausted from the currentremaining amount. For example, when passing close to a parking positionfor unloading during autonomous travel, whether having the harvester 1pass the parking position and then deviate after becoming full andreturn to the parking position or having the harvester 1 unload whilepassing nearby the parking position will ultimately be more efficienttravel (whether the total work time is shorter, the total traveldistance is shorter, and so on) is determined on the basis of themargin, the time required for the unloading work, and the like. Carryingout the unloading work when there is a very small amount of harvestedcrops increases the overall number of instances of unloading, and isthus inefficient, whereas if the tank is almost full, it is moreefficient to unload at that time.

(A8) FIG. 18 illustrates a case where the travel route element selectedin work travel resumed after departing the area CA to be worked is not acontinuation of the pre-departure work travel. In this case, a linearback-and-forth travel pattern such as that illustrated in FIGS. 3 and 12is set in advance. In FIG. 18, the parking position is indicated by thesign PP, and a travel route in a case where work travel was successfullycompleted for the area CA to be worked through linear back-and-forthtravel involving 180° U-turn travel is indicated by a dotted line as acomparative example. The actual travel trajectory is indicated by a boldsolid line. As the work travel progresses, the straight line-shapedtravel route elements and the U-turn travel route are selected insequence (step #01).

When a departure request is issued midway through the work travel (step#02), a travel route progressing from the area CA to be worked to theouter peripheral area SA is calculated. At this point, two routes areconceivable: a route in which the harvester 1 continues to progressalong the travel route element currently being traveled and exits to theouter peripheral area SA; and a route in which the harvester 1 turns 90°from the travel route element currently being traveled, passes throughan already-harvested site (=an aggregate of travel route elements having“already traveled” attributes), and exits to the outer peripheral areaSA where the parking position is located. Here, the latter route, whichhas a shorter travel distance, is selected (step #03). In this latterinstance of departure travel, an element obtained by moving a travelroute element set in the outer peripheral area SA parallel as far as thedeparture point is used as a departure travel route element in the areaCA to be worked after the 90° turn. However, if the departure request ismade with leeway in terms of time, the former route is selected. In theformer instance of departure travel, the harvesting work is continuedduring the departure travel in the area CA to be worked, which isbeneficial in terms of the work efficiency.

Upon deviating from the work travel in the area CA to be worked,executing departure travel through the area CA to be worked and theouter peripheral area SA, and reaching the parking position, theharvester 1 receives support from the work support vehicle. In thisexample, the harvested crops held in the harvested crop tank 14 areunloaded to the transport vehicle CV.

Once the harvested crops have been completely unloaded, it is necessaryto return to the point where the departure request was issued, in orderto return to the work travel. In the example of FIG. 18, an unworkedpart remains in the travel route element that was being traveled whenthe departure request was issued, and thus the harvester 1 returns tothat travel route element. Accordingly, the harvester 1 selects a travelroute element in the outer peripheral area SA from the parking position,travels counterclockwise, and upon reaching the endpoint of the targettravel route element, turns by 90° at that point, enters the travelroute element, and executes the work travel. If the point where thedeparture request was made has been passed, the harvester 1 travelswithout working, passes through a U-turn travel route, and then executeswork travel for the next travel route element (step #04). The harvester1 then continues with linear back-and-forth travel, and completes thework travel in the area CA to be worked (step #05).

(A9) If the position of a travel obstacle within the field is includedin the inputted work site data, or if the harvester 1 includes anobstacle position detection device, a travel route element for obstacleavoidance travel is selected on the basis of the position of theobstacle and the host vehicle position. The selection rules for avoidingan obstacle include a rule that selects travel route elements providinga circumventing route that comes as close as possible to the obstacle, arule that selects travel route elements so that the harvester 1 firstexits to the outer peripheral area SA and then follows a linear routewhere no obstacle is present when entering the area CA to be worked, andso on.

(A10) If, when a spiral travel pattern such as that illustrated in FIGS.4 and 11 is set, the travel route element to be selected is short, thespiral travel pattern is automatically changed to the linearback-and-forth travel pattern. This is because when the surface area islimited, spiral travel including α-turn travel carried out forward andin reverse tends to be inefficient.

(A11) If, when traveling through traditional travel, the number ofunworked sites, i.e., the number of unworked (untraveled) travel routeelements in the travel route element set of the area CA to be worked,has become less than or equal to a predetermined number, the traditionaltravel is automatically switched to autonomous travel. Additionally, ifthe harvester 1 is working through spiral travel from the outside towardthe inside of an area CA to be worked that is covered by a mesh lineset, the travel pattern is automatically switched from a spiral travelpattern to a linear back-and-forth travel pattern when the surface areaof the remaining unworked site has become small and the number ofunworked travel route elements has become less than or equal to apredetermined value. In this case, as described above, a travel routeelement having the “intermediate straight route” attribute is movedparallel from the outer peripheral area SA to the vicinity of theunworked site in the area CA to be worked, in order to avoid wastefultravel.

(A12) In fields of rice, wheat, or the like, causing the harvester 1 totravel parallel to the rows (furrows) where seedlings are planted canimprove the efficiency of the harvesting work. Thus in the selection oftravel route elements by the route element selecting unit 63, a travelroute element that is closer to being parallel to the rows is made morelikely to be selected. However, if, when starting the work travel, themachine is not in an attitude or position parallel to the roaddirection, the configuration is such that travel for bringing themachine to an attitude parallel to the rows is executed while workingeven if that travel follows the direction intersecting with the roaddirection. This makes it possible to reduce wasteful travel (non-worktravel) and end the work quickly.

Cooperative Travel Control

Work travel in the work vehicle automatic traveling system when aplurality of work vehicles are introduced will be described next. Forthe sake of simplicity, a case where two harvesters 1 execute worktravel (autonomous travel) will be described here. FIG. 19 illustrates afirst work vehicle functioning as a master harvester 1 m, and a secondwork vehicle functioning as a slave harvester 1 s, executing work travelin a single field in cooperation with each other. Although the twoharvesters 1 are given the names “master harvester 1 m” and “slaveharvester 1 s” to distinguish between the two, these may simply bereferred to as “harvesters 1” when it is not necessary to distinguishbetween the two. A monitoring party occupies the master harvester 1 m,and the monitoring party operates the communication terminal 4 whichs/he has brought into the master harvester 1 m. The terms “master” and“slave” are used here for the sake of simplicity, but these do notindicate a master/slave relationship; rather, the master harvester 1 mand the slave harvester 1 s execute autonomous travel with independentroutes set on the basis of the above-described travel route settingroutines (the travel route element selection rules). However, datacommunication can be carried out between the master harvester 1 m andthe slave harvester 1 s through the respective communication processingunits 70, and state information, corresponding to the work travelstates, can be exchanged. The communication terminal 4 can not onlysupply commands from the monitoring party and data pertaining to thetravel route to the master harvester 1 m, but can also supply commandsfrom the monitoring party and data pertaining to the travel route to theslave harvester 1 s via the communication terminal 4 and the masterharvester 1 m. For example, the state information output from the workstate evaluating unit 55 of the slave harvester 1 s is also transferredto the master harvester 1 m, and the state information output from thework state evaluating unit 55 of the master harvester 1 m is alsotransferred to the slave harvester 1 s. Accordingly, both route elementselecting units 63 have functions for selecting the next travel routeelements in consideration of both instances of state information andboth host vehicle positions. When the route managing unit 60 and theroute element selecting unit 63 are provided in the communicationterminal 4, both harvesters 1 supply the state information to thecommunication terminal 4 and receive the next travel route elementselected there.

Like FIG. 7, FIG. 20 illustrates an area CA to be worked, which iscovered by a mesh line set constituted by mesh lines dividing the areainto a mesh by the work width, being worked by two harvesters 1, i.e.,by the master harvester 1 m and the slave harvester 1 s. Here, themaster harvester 1 m enters the travel route element L11 from thevicinity of a lower-right corner of the deformed quadrangle representingthe area CA to be worked, turns left at the point of intersectionbetween the travel route element L11 and the travel route element L21,and enters the travel route element L21. Furthermore, the masterharvester 1 m turns left at the point of intersection between the travelroute element L21 and the travel route element L32, and then enters thetravel route element L32. In this manner, the master harvester 1 mexecutes spiral travel using left turns. On the other hand, the slaveharvester 1 s enters the travel route element L31 from the vicinity ofan upper-left corner of the area CA to be worked, turns left at thepoint of intersection between the travel route element L31 and thetravel route element L41, and enters the travel route element L41.Furthermore, the slave harvester 1 s turns left at the point ofintersection between the travel route element L41 and the travel routeelement L12, and then enters the travel route element L12. In thismanner, the slave harvester 1 s executes spiral travel using left turns.As is clear from FIG. 20, cooperative control is carried out so that thetravel trajectories of the slave harvester 1 s enter between the traveltrajectories of the master harvester 1 m. Accordingly, the travel of themaster harvester 1 m is spiral travel that leaves an interval equivalentto the combined width of its own work width and the work width of theslave harvester 1 s. Likewise, the travel of the slave harvester 1 s isspiral travel that leaves an interval equivalent to the combined widthof its own work width and the work width of the master harvester 1 m.The travel trajectories of the master harvester 1 m and the traveltrajectories of the slave harvester 1 s form a double spiral.

Because the area CA to be worked is defined by the outer peripheral areaSA formed by circling travel on the outside, it is necessary for thefirst circling travel for forming the outer peripheral area SA to becarried out by either the master harvester 1 m or the slave harvester 1s. This circling travel can also be executed through cooperative controlof the master harvester 1 m and the slave harvester 1 s.

In this manner, when the route element selecting unit 63 employs thecooperative route element selection rule, the travel route elements areselected so that the plurality of harvesters 1 carry out work travelcooperatively in the area CA to be worked, as illustrated in FIG. 20,for example. As a result, in the example of FIG. 20, the two traveltrajectories of the two harvesters 1 are spiral travel patterns thatcover the area CA to be worked while tracing a double spiral line. Whenthe route element selecting unit 63 employs the independent routeelement selection rule, the travel route elements are selected so that asingle harvester 1 carries out work travel in the area CA to be worked,as illustrated in FIG. 11, for example. As a result, in the example ofFIG. 11, the one travel trajectory of the one harvester 1 is a spiraltravel pattern that covers the area CA to be worked while tracing aspiral line.

Next, switching from cooperative work travel for two harvesters 1 usingthe cooperative route element selection rule, to independent work travelfor a single harvester 1 using the independent route element selectionrule, will be described using FIG. 21. The switch from cooperative worktravel to independent work travel occurs when one of the harvesters 1stops or departs the area CA to be worked.

Note that the travel trajectories illustrated in FIG. 20 are theoreticaltrajectories. In reality, the travel trajectory of the master harvester1 m and the travel route of the slave harvester 1 s are corrected inaccordance with the state information output from the work stateevaluating units 55 (including the other vehicle positional relationshipand the estimated contact position), and those travel trajectories donot constitute a perfect double spiral. One example of such correctedtravel will be described next using FIG. 21.

The switch from cooperative work travel to independent work travel isexecuted upon it being confirmed that one of the harvesters 1 hasstopped or departed the area CA to be worked, on the basis of the stateinformation output from the work state evaluating units 55 (includingthe other vehicle positional relationship and the estimated contactposition). In FIG. 21, the transport vehicle CV, which transportsharvested crops harvested by the harvesters 1, is parked at a positioncorresponding to the outside center of the first side S1, on the outside(the ridge) of the field. A parking position where the harvesters 1 areto park to unload the harvested crops to the transport vehicle CV is setto a position in the outer peripheral area SA that is adjacent to thetransport vehicle CV. FIG. 21 illustrates a state where the slaveharvester 1 s departs from the travel route element in the area CA to beworked midway through the work travel, executes circling travel aroundthe outer peripheral area SA, unloads the harvested crops into thetransport vehicle CV, once again executes circling travel around theouter peripheral area SA, and returns to the travel route element in thearea CA to be worked.

First, once a departure request (for unloading harvested crops) has beenissued, the route element selecting unit 63 of the slave harvester 1 sselects a travel route element having a “departure route” attributevalue in the outer peripheral area SA and a travel route element fordeparting to the travel route element having the “departure route”attribute, on the basis of the margin for the held amount of crops, thetravel distance to the parking position, and so on. In this embodiment,a travel route element set in the area of the outer peripheral area SAwhere the parking position is set, and the travel route element L41currently being traveled, are selected, and the point of intersectionbetween the travel route element L41 and the travel route element L12serve as the departure point. Having progressed to the outer peripheralarea SA, the slave harvester 1 s travels along the travel route elementin the outer peripheral area SA (the departure route) to the parkingposition, and unloads the harvested crops to the transport vehicle CV atthe parking position. Such data indicating that the slave harvester ishas departed the area CA to be worked is determined from the currentposition of the slave harvester 1 s and the travel route elementcurrently selected by the slave harvester 1 s, and the current positionof the master harvester 1 m and the travel route element currentlyselected by the master harvester 1 m, which are included in the stateinformation output from the work state evaluating units 55.

The master harvester 1 m continues work travel in the area CA to beworked even while the slave harvester 1 s is unloading the harvestedcrops after deviating from the work travel in the area CA to be worked.However, it was originally assumed that the master harvester 1 m wouldselect the travel route element L13 at the point of intersection betweenthe travel route element L42 and the travel route element L13 whiletraveling along the travel route element L42. However, the travel of theslave harvester 1 s along the travel route element L12 has been canceleddue to the departure of the slave harvester 1 s, and thus the travelroute element L12 is an unharvested area (untraveled). Accordingly, theroute element selecting unit 63 of the master harvester 1 m cancels thecooperative route element selection rule and instead employs theindependent route element selection rule. As a result, the route elementselecting unit 63 of the master harvester 1 m selects the travel routeelement L12 instead of the travel route element L13. In other words, themaster harvester 1 m travels to the point of intersection between thetravel route element L42 and the travel route element L12, turns left,and travels along the travel route element L12.

When the slave harvester 1 s finishes unloading the harvested crops, theroute element selecting unit 63 of the slave harvester 1 s selects thetravel route elements to return along, on the basis of the currentposition and autonomous travel speed of the slave harvester 1 s, theattributes of the travel route element in the area CA to be worked(untraveled/already traveled), the current position and autonomoustravel speed of the master harvester 1 m, and so on. In this embodiment,the travel route element L43, which is the unworked travel route elementlocated furthest on the outside, is selected. The slave harvester 1 stravels through the outer peripheral area SA from the parking position,in the counterclockwise direction, along the travel route element havinga “return route” attribute, and enters the travel route element L43 fromthe left end of the travel route element L43. Once the route elementselecting unit 63 of the slave harvester 1 s selects the travel routeelement L43, that information is sent to the master harvester 1 m asstate information. Accordingly, the route element selecting unit 63 ofthe master harvester 1 m cancels the independent route element selectionrule and instead employs the cooperative route element selection rule.As a result, assuming a travel route up to the travel route element L33had been selected, the route element selecting unit 63 of the masterharvester 1 m selects the travel route element L44 adjacent to thetravel route element L43 on the inner side as the next travel routeelement. As this time, the other vehicle positional relationshipcalculating unit 56 estimates that the master harvester 1 m and theslave harvester 1 s will make contact near the point of intersectionbetween the travel route element L33 and the travel route element L44currently being traveled (selected) by the master harvester 1 m and theslave harvester 1 s. As a result, the other vehicle positionalrelationship calculating unit 56 calculates the vicinity of that pointof intersection as the estimated contact position. Accordingly, theother vehicle positional relationship calculating unit 56 calculates adifference in the time when the master harvester 1 m and the slaveharvester 1 s will pass near that point of intersection, and if the timedifference is less than or equal to a predetermined value (if it isestimated that the master harvester 1 m and the slave harvester 1 s willcome into contact), sends a command to the autonomous travel controllingunit 511 so that the harvester 1 which passes later (the masterharvester 1 m, here) stops temporarily to avoid a collision. After theslave harvester 1 s has passed that point of intersection, the masterharvester 1 m once again starts the autonomous travel. In this manner,the master harvester 1 m and the slave harvester 1 s exchangeinformation such as the host vehicle positions, the selected travelroute elements, and so on, and thus collision avoidance behavior, delayavoidance behavior, and so on can be executed.

Such collision avoidance travel, delay avoidance travel, and so on arealso executed during linear back-and-forth travel, as indicated in FIGS.22 and 23. At this time, a switch from the cooperative route elementselection rule to the independent route element selection rule and viceversa are also executed. In FIGS. 22 and 23, a parallel straight lineset constituted by mutually-parallel straight lines is indicated by L01,L02, . . . , L10, where L01 to L04 are already-worked travel routeelements, and L05 to L10 are unworked travel route elements. In FIG. 22,the master harvester 1 m travels along the outer peripheral area SA inorder to approach the parking position indicated by the double-dot-dashline. To avoid contact with the master harvester 1 m, the slaveharvester 1 s stops temporarily at a lower end of the area CA to beworked, specifically, a lower end of the travel route element L04, ascollision avoidance behavior. In FIG. 23, the master harvester 1 m thathas passed in front of the slave harvester 1 s is stopped at the parkingposition. Additionally, in the work travel state illustrated in FIGS. 22and 23, the route element selecting unit 63 of the slave harvester 1 semploys the independent route element selection rule. The route elementselecting unit 63 of the master harvester 1 m employs a departure routeelement selection rule for selecting a circling route element. In FIG.23, if the slave harvester 1 s enters the outer peripheral area SA fromthe travel route element L04 through U-turn travel in order to move tothe travel route element L07, the slave harvester 1 s will collide withthe master harvester 1 m. If the master harvester 1 m is parked at theparking position, it is not possible to enter the area CA to be workedor depart from the area CA to be worked using the travel route elementsL05, L06, and L07, and thus the travel route elements L05, L06, and L07are temporarily set to “travel prohibited” (prohibited from selection).Once the master harvester 1 m finishes unloading and moves from theparking position, the route element selecting unit 63 of the slaveharvester 1 s selects the travel route element to be moved to next fromamong the travel route elements L05 to L10, in light of the travel routeof the master harvester 1 m, after which the slave harvester 1 s resumesautonomous travel.

It is also possible for the slave harvester 1 s to continue workingwhile the master harvester 1 m is unloading or the like at the parkingposition. FIG. 23 illustrates an example thereof. In this case, theroute element selecting unit 63 of the slave harvester 1 s wouldnormally select the travel route element L07, which is three lanes aheadand has a travel route element priority level of 1, as the travel routeelement to be moved to. However, the travel route element L07 is set to“travel prohibited”, in the same manner as the example illustrated inFIG. 22. Accordingly, the travel route element L08, which has thenext-highest priority level, is selected. Multiple routes are calculatedas routes for moving from the travel route element L04 to the travelroute element L08, such as a route that reverses along the currenttravel route element L04 that is now already traveled (indicated by asolid line in FIG. 23), a route that travels clockwise from the lowerend of the travel route element L04 and advances into the outerperipheral area SA (indicated by a dotted line in FIG. 23), and so on,and the most efficient route, e.g., the shortest route (the routeindicated by the solid line, in this embodiment), is selected.

The following can be understood from the form of the work travelillustrated in FIGS. 22 and 23. That is, under the cooperative routeelement selection rule, a travel route element where a harvester 1 asidefrom the host vehicle is located, and a travel route element adjacent tothat travel route element, are excluded from the next travel routeelement to be selected. Under the independent route element selectionrule, the travel route element for moving toward a harvester 1 asidefrom the host vehicle, located in the outer peripheral area, is excludedfrom the next travel route element to be selected.

As described above, even when multiple harvesters 1 cooperate for worktravel in a single field, the respective route element selecting units63 select the travel route elements in sequence on the basis of travelpatterns manually input from a work plan manual received from themanagement center KS or received from the communication terminal 4(e.g., a linear back-and-forth travel pattern or a spiral travelpattern), the host vehicle positions, state information output from therespective work state evaluating units 55, and pre-registered selectionrules. Selection rules (B1) to (B11), which are different from theabove-described rules (A1) to (A12) and that apply specifically whenmultiple harvesters 1 execute work travel in cooperation with eachother, will be described below.

(B1) The multiple harvesters 1 executing work travel in cooperation witheach other travel autonomously along the same travel pattern. Forexample, if a linear back-and-forth travel pattern is set for one of theharvesters 1, a linear back-and-forth travel pattern is also set for theother harvester 1.

(B2) If, when a spiral travel pattern is set, one of the harvesters 1deviates from the work travel in the area CA to be worked and enters theouter peripheral area SA, the other harvester 1 selects a travel routeelement further on the outside. As a result, instead of allowing theroute that the departed harvester 1 had planned to travel to remain, thedeparted harvester 1 enters the planned travel route element first.

(B3) If a spiral travel pattern is set, when a harvester 1 that hasdeparted once again returns to the work travel in the area CA to beworked, a travel route element that is far from the harvester 1 engagedin the work travel and that has an “unworked” attribute is selected.

(B4) If, when a spiral travel pattern is set, the travel route elementto be selected become shorter, the work travel is executed by only oneof the harvesters 1, and the remaining harvester 1 deviates from thework travel.

(B5) When a spiral travel pattern is set, the multiple harvesters 1 areprohibited from simultaneously selecting a travel route element from atravel route element set parallel to a side of the polygon expressingthe outer shape of the area CA to be worked, in order to avoid the riskof the collision.

(B6) When a linear back-and-forth travel pattern is set, and one of theharvesters 1 is engaged in U-turn travel, the autonomous travel iscontrolled so that the other harvester 1 does not enter into the area ofthe outer peripheral area SA where the U-turn travel is being executed.

(B7) When a linear back-and-forth travel pattern is set, a travel routeelement located at least two spaces from the travel route element thatthe other harvester 1 plans to travel next, or the travel route elementthat the other harvester 1 is currently traveling, is selected as thenext travel route element.

(B8) The determination of the timing at which to deviate from the worktravel in the area CA to be worked, and the selection of the travelroute elements, for the purpose of unloading harvested crops orrefueling, is carried out based not only on the margin and the traveltime to the parking position, but also under the condition that multipleharvesters 1 do not depart at the same time.

(B9) If the master harvester 1 m is set to traditional travel, the slaveharvester 1 s executes autonomous travel so as to follow the masterharvester 1 m.

(B10) If the capacity of the harvested crop tank 14 in the masterharvester 1 m is different from the capacity of the harvested crop tank14 in the slave harvester 1 s, and the harvesters 1 make unload requestsat the same time or almost the same time, the harvester 1 having thelower capacity unloads first. This shortens the unload standby time(downtime) of the harvester 1 that cannot unload, and makes it possibleto finish the harvesting work in the field even slightly more quickly.

(B11) When a single field is very large, that field is segmented intomultiple segments through a middle dividing process, and a harvester 1is deployed in each of the segments. FIG. 24 is a diagram illustrating astate midway through a middle dividing process, in which a band-shapedmiddle-divided area CC is formed in the center of the area CA to beworked and the area CA to be worked is segmented into two segments CA1and CA2. FIG. 25 is a diagram illustrating a state after the middledividing process has ended. In this embodiment, the master harvester 1 mforms the middle-divided area CC. While the master harvester 1 m isexecuting the middle dividing, the slave harvester 1 s executes worktravel in segment CA2 according to a linear back-and-forth travelpattern, for example. Before this work travel is executed, a travelroute element set is generated for the segment CA2. At this time,selecting the travel route element corresponding to one work widthlocated closest to the middle-divided area CC in the segment CA2 isprohibited until the middle dividing process ends. This makes itpossible to ensure that the master harvester 1 m and the slave harvester1 s do not make contact.

Once the middle dividing process ends, the travel of the masterharvester 1 m is controlled so as to execute independent work travelusing a travel route element set calculated for the segment CA1, whereasthe travel of the slave harvester 1 s is controlled so as to executeindependent work travel using a travel route element set calculated forthe segment CA2. If one of the harvesters 1 has completed the workfirst, that harvester 1 enters the segment in which work remains, andcooperative control with the other harvester 1 is started. The harvester1 that has completed the work in the segment it handles travelsautonomously to the segment handled by the other harvester 1 in order toassist in the other harvester 1 in its work.

If the field has an even larger scale, the field is middle-divided intoa grid shape, as illustrated in FIG. 26. This middle dividing can becarried out by the master harvester 1 m and the slave harvester 1 s. Thesegments formed by middle-dividing the field into a grid shape areassigned to be worked by the master harvester 1 m or the slave harvester1 s, and the work travel is executed by a single harvester 1 in each ofthose segments. However, the travel route elements are selected underthe condition that the master harvester 1 m and the slave harvester isare not distanced from each other by greater than or equal to apredetermined value. This is because it is difficult for the monitoringparty occupying the master harvester 1 m to monitor the work travel ofthe slave harvester 1 s, for the state information to be exchangedbetween the machines, and so on if the slave harvester 1 s and themaster harvester 1 m are too far apart. With a situation such as thatillustrated in FIG. 26, the harvester 1 that has finished work in thesegment it handles may autonomously travel to the segment handled by theother harvester 1 to assist the other harvester 1 in its work, or mayautonomously travel to the next segment it handles itself.

The parking position of the transport vehicle CV, the parking positionof the refueling vehicle, and so on are outside the outer peripheralarea SA, and thus depending on the segment in which work travel isunderway, the travel route for unloading harvested crops or refuelingmay become longer and result in wasteful travel time. Thus whentraveling to the parking position and returning from the parkingposition, travel route elements for segments in which work travel is tobe executed while passing through, and circling route elements, areselected.

Fine Adjustments to Parameters of Work Machine Device Groups, etc.during Cooperative Autonomous Travel

When the master harvester 1 m and the slave harvester 1 s execute worktravel cooperatively, the monitoring party normally occupies the masterharvester 1 m. As such, for the master harvester 1 m, the monitoringparty can make fine adjustments to the values of autonomous travelcontrol parameters for the vehicle travel device group 71, the workdevice group 72, and so on as necessary by using the communicationterminal 4. The values of the parameters for the vehicle travel devicegroup 71, the work device group 72, and so on of the master harvester 1m can also be applied in the slave harvester 1 s, and thus aconfiguration in which the parameters of the slave harvester 1 s can beadjusted from the master harvester 1 m can be employed, as illustratedin FIG. 27. However, there is no problem if the slave harvester 1 sincludes a communication terminal 4 as well. This is because the slaveharvester 1 s may also execute autonomous travel independently, and maybe used as the master harvester 1 m as well.

The communication terminal 4 illustrated in FIG. 27 is provided with aparameter obtaining unit 45 and a parameter adjustment commandgenerating unit 46. The parameter obtaining unit 45 obtains deviceparameters set by the master harvester 1 m and the slave harvester 1 s.As a result, the values set for the device parameters of the masterharvester 1 m and the slave harvester 1 s can be displayed in thedisplay panel unit of the touch panel 41 in the communication terminal4. The monitoring party occupying the master harvester 1 m inputs adevice parameter adjustment amount for adjusting the device parametersof the master harvester 1 m and the slave harvester 1 s through thetouch panel 41. On the basis of the input device parameter adjustmentamount, the parameter adjustment command generating unit 46 generates aparameter adjustment command for adjusting the corresponding deviceparameters, and sends that command to the master harvester 1 m and theslave harvester 1 s. As a communication interface for suchcommunication, the control units 5 of the master harvester 1 m and theslave harvester 1 s include the communication processing unit 70, andthe communication terminal 4 includes the communication control unit 40.To adjust the device parameters of the master harvester 1 m, themonitoring party may use various types of operation implements providedin the master harvester 1 m to make the adjustments directly. The deviceparameters are divided into travel device parameters and work deviceparameters. The travel device parameters include the vehicle speed andthe engine RPM. The work device parameters include the height of theharvesting section 15, the height of the reel 17, and so on.

As described above, the other vehicle positional relationshipcalculating unit 56 has a function for calculating the current positionand actual vehicle speed of the harvester 1 on the basis of thepositioning data obtained by the satellite positioning module 80. Duringcooperative autonomous travel, this function is used to compare theactual vehicle speed based on the positioning data of the harvester 1that is leading in one direction with the actual vehicle speed based onthe positioning data of the harvester 1 that is following, and if thereis a difference in vehicle speeds, the vehicle speeds are adjusted sothat the vehicle speed of the following harvester 1 matches the vehiclespeed of the leading harvester 1. This prevents abnormal proximities,contact, and so on caused by differences in the vehicle speeds of theleading harvester 1 and the following harvester 1.

As described above, even if one harvester 1 has departed while the twoharvesters 1 are midway through cooperative work travel, switching fromthe cooperative route element selection rule to the independent routeelement selection rule makes it possible for the other harvester 1 tocarry out the work travel of the one work vehicle 1. Likewise, even ifat least one harvester 1 has departed while three or more harvesters 1are midway through cooperative work travel, switching to a cooperativeroute element selection rule with a lower number of harvesters 1 or tothe independent route element selection rule makes it possible for theremaining harvesters 1 to carry out the work travel of the departed workvehicle 1.

The communication processing unit 70 of the harvester 1, thecommunication control unit 40 of the communication terminal 4, and so oncan be provided with data and voice communication functions for makingcalls, sending emails, and so on to registered mobile communicationterminals such as mobile phones. When such a data and voicecommunication function is provided, if the held amount of harvestedcrops exceeds a predetermined amount, a call (artificial voice) or anemail indicating that the harvested crops are to be unloaded is sent tothe driver of the transport vehicle CV where the harvested crops are tobe unloaded. Likewise, if the remaining fuel has dropped below apredetermined amount, a call (artificial voice) or an email indicating arequest to refuel is sent to the driver of the refueling vehicle.

Other Embodiments

(1) The foregoing embodiments describe autonomous travel assuming that asufficiently broad space for U-turn travel during linear back-and-forthtravel and α-turn travel during spiral travel has been secured throughthe peripheral travel executed in advance. However, U-turn traveltypically requires more space than α-turn travel. Accordingly, it may bethe case that the space formed through the circling travel executed inadvance is insufficient for U-turn travel. For example, when a singleharvester 1 is working, there is a risk that a divider or the like willmake contact with a ridge and damage the ridge during U-turn travel, asindicated in FIG. 28. Accordingly, to avoid such a situation where theridge is damaged when a linear back-and-forth travel pattern is set asthe travel pattern, when the work travel is started, the outerperipheral area SA is first expanded inward by automatically making atleast one pass of work travel in the outermost peripheral part of thearea CA to be worked. Even if the width of the outer peripheral area SAformed through the circling travel executed in advance is insufficientfor U-turn travel, expanding the outer peripheral area SA inward in thismanner makes it possible to execute U-turn travel with no problems.Additionally, when stopping the harvester 1 at a specified parkingposition to unload harvested crops to a work support vehicle stopped inthe periphery of the field or the like, it is necessary, to ensure theefficiency of the work, to stop the harvester 1 at the parking positionwith a certain degree of accuracy and in an attitude (orientation)suited to the support work. This is true for both autonomous travel andmanual travel. Of the outer peripheral lines of the area CA to beworked, the outer peripheral line on the side where the U-turn travel isexecuted does not vary depending on the linear back-and-forth travel.Thus if the outer peripheral area SA is narrow, there is a chance thatthe harvester 1 will collide with the area CA to be worked, which is anunworked site, and damage the crops, make contact with the ridge anddamage the ridge, and so on. Accordingly, before starting the worktravel of the area CA to be worked through linear back-and-forth travel,it is preferable to execute an additional instance of circling travel(additional circling travel). This additional circling travel may becarried out in response to an instruction from the monitoring party, ormay be carried out automatically. Note that as described above, thecircling travel executed in advance to create the outer peripheral areaSA is normally carried out through multiple passes in a spiral shape.The outermost circling travel route has a complex travel route anddiffers from field to field, and thus manual steering is employed. Thesubsequent circling travel is carried out through autonomous steering ormanual steering. Additionally, if the parking position PP and a U-turnroute set UL overlap, a situation is conceivable where a harvester 1obstructs the U-turn travel of another harvester 1 while the firstharvester 1 is parked at the parking position PP, as illustrated in FIG.28. Accordingly, if the parking position PP and the U-turn route set ULoverlap at the point in time when the advance circling travel iscomplete, it is desirable that the above-described additional circlingtravel be executed.

The travel route for the additional circling travel can be calculated onthe basis of the travel trajectory of the harvester 1 in the advancecircling travel, the outer shape data of the area CA to be worked, andso on. As such, the additional circling travel can be carried outthrough autonomous steering. An example of the flow of additionalperipheral travel executed through autonomous travel will be describedbelow using FIG. 28.

Step #01

The field is segmented into the outer peripheral area SA, where theharvesting work is complete, and the area CA to be worked, where theharvesting work is to be carried out next, through the advance circlingtravel. After the advance peripheral travel, the parking position PP andthe U-turn route set UL overlap in the outer peripheral area SA, asindicated by step #01 in FIG. 28. The width of the part of the outerperipheral area SA where the U-turn route set UL is set will not beexpanded by linear back-and-forth travel alone. As such, the additionalperipheral travel indicated by step #02 in FIG. 28 is executedautomatically or in response to an instruction from the monitoring partyso as to expand the width of that part.

Step #02

In this additional peripheral travel, multiple peripheral travel routeelements (indicated by bold lines in FIG. 28), constituting arectangular peripheral travel route, are calculated. These circlingtravel route elements include a left-end travel route element Ls and aright-end travel route element Le of the travel route elementscalculated for the linear back-and-forth travel. Note that the travelroute element Ls and the travel route element Le are both straightlines. Additionally, in the rectangular circling travel route, thetravel route element Ls and the travel route element Le are oppositesides. Here, the circling travel route elements are the travel routeelement Ls, the travel route element Le, a travel route elementconnecting the upper ends of the travel route element Ls and the travelroute element Le, and a travel route element connecting the lower endsof the travel route element Ls and the travel route element Le. Once theautonomous travel is started, the circling travel route elementsconforming to this additional circling travel route are selected by theroute element selecting unit 63, and the autonomous travel (work travelexecuted during the circling travel) is executed.

Step #03

As indicated by step #03 in FIG. 28, the outer peripheral area SA isexpanded as a result of this additional peripheral travel. Accordingly,a space having a width corresponding to at least the work width of theharvester 1 is newly formed between the parking position PP and theunworked site. Next, as a result of the area CA to be worked beingreduced by an amount equivalent to the same number of work widths asthere were instances of the additional circling travel, the left-endtravel route element Ls and the right-end travel route element Le moveinward by an amount equivalent to the reduction in the area CA to beworked. A work travel route according to a linear back-and-forth travelpattern is then determined for the new area CA to be worked, which is arectangle taking the moved travel route element Ls and travel routeelement Le as opposite sides, and the autonomous work travel is startedin the new area CA to be worked.

Note that in step #01 of FIG. 28, there are cases where the parkingposition PP does not overlap with the U-turn route set UL, and theparking position PP does not face the U-turn route set UL. For example,there are cases where the parking position PP is in a position facingthe left-end travel route element Ls. In this case, the area in theperiphery of the parking position is expanded by executing the linearback-and-forth travel in which the travel route element Ls is firstselected, and thus the above-described additional circling travel is nolonger executed. Alternatively, only approximately one pass of theadditional circling travel may be executed.

The configuration may also be such that the above-described additionalcircling travel is carried out automatically even when multipleharvesters 1 execute work travel cooperatively. In cooperative work,when a linear back-and-forth travel pattern is set as the travel patternand the parking position PP is set to a position facing the U-turn routeset UL, multiple passes (approximately three to four passes) of theadditional circling travel are executed automatically, immediately afterthe work travel is started. As a result, the area CA to be worked isreduced, and a broad space is secured on the inner side of the parkingposition PP. Thus even if one harvester 1 is stopped in the parkingposition PP, another harvester 1 can make a U-turn on the innercircumferential side of the parking position PP, can pass on the innercircumferential side of the parking position PP, and so on with leeway.

(2) In the above-described embodiment, the configuration is such thatif, when a linear back-and-forth travel pattern is set, the parkingposition PP for work involving a support vehicle such as the transportvehicle CV is set in an area of the outer peripheral area SA whereU-turn travel is executed, a harvester 1, which is different from theharvester 1 stopped for unloading work or the like, stops until the endof the unloading work or the like and stands by, selects a travel routeelement that circumvents the parking position PP, or the like. However,the configuration may be such that in this case, if the autonomoustravel (work travel) is started in order to secure a sufficient spacefor executing U-turn travel further inward from the parking position PP,one or more of the harvesters 1 automatically make several passes of thecircling travel in an outer peripheral part of the area CA to be worked.

(3) The foregoing embodiment describes setting and selecting travelroute elements while treating the work widths of the master harvester 1m, which is the first work vehicle, and the slave harvester 1 s, whichis the second work vehicle, as being the same. Two examples of methodsfor setting and selecting the travel route elements when the work widthof the master harvester 1 m is different from the work width of theslave harvester 1 s will be described here. The work width of the masterharvester 1 m will be described as a first work width, and the workwidth of the slave harvester 1 s will be described as a second workwidth. For the sake of simplicity, the first work width willspecifically be referred to as “6”, and the second work width as “4”.

(3-1) FIG. 29 illustrates an example of a case where a linearback-and-forth travel pattern is set. In this case, the route managingunit 60 calculates the travel route element set, which is an aggregateof multiple travel route elements covering the area CA to be worked, ata reference width, which is the greatest common divisor or anapproximate greatest common divisor of the first work width and thesecond work width. Because the first work width is “6” and the secondwork width is “4”, the reference width is “2”. In FIG. 29, numbers from01 to 20 are added to the travel route elements as route numbers inorder to identify the travel route elements.

Assume that the master harvester 1 m departs from the travel routeelement having a route number of 17, and the slave harvester 1 s departsfrom the travel route element having a route number of 12. Asillustrated in FIG. 6, the route element selecting unit 63 is dividedinto a first route element selecting unit 631, which has a function forselecting the travel route elements for the master harvester 1 m, and asecond route element selecting unit 632, which has a function forselecting the travel route elements for the slave harvester 1 s. If theroute element selecting unit 63 is provided in the control unit 5 of themaster harvester 1 m, the next travel route element selected by thesecond route element selecting unit 632 is supplied to the route settingunit 64 of the slave harvester 1 s via the communication processing unit70 of the master harvester 1 m and the communication processing unit 70of the slave harvester 1 s. Note that it is not absolutely necessary forthe center of the work width or the center of the harvester 1 to matchthe travel route element, and if there is deviation, the autonomoustravel is controlled in accordance with that deviation.

As illustrated in FIG. 29, the first route element selecting unit 631selects the next travel route element from an untraveled travel routeelement set so as to leave an area equivalent to an integral multiple ofthe first work width or the second work width (this may be untraveled oralready traveled) or an area equivalent to the total of an integralmultiple of the first work width and an integral multiple of the secondwork width (this may be untraveled or already traveled). The selectednext travel route element is supplied to the route setting unit 64 ofthe master harvester 1 m. Likewise, the second route element selectingunit 632 selects the next travel route element from an untraveled travelroute element set so as to leave an area equivalent to an integralmultiple of the first work width or the second work width (this may beuntraveled or already traveled) or an area equivalent to the total of anintegral multiple of the first work width and an integral multiple ofthe second work width (this may be untraveled or already traveled).

In other words, an untraveled area having a width that is an integralmultiple of the first work width or the second work width remains in thearea CA to be worked after the master harvester 1 m or the slaveharvester 1 s has executed autonomous travel along the next travel routeelement supplied by the first route element selecting unit 631 or thesecond route element selecting unit 632. Although it is possible that anunworked area having a width narrower than the second work width willultimately remain, the unworked area that ultimately remains issubjected to work travel by the master harvester 1 m or the slaveharvester 1 s.

(3-2) FIG. 30 illustrates an example of a case where a spiral travelpattern is set. In this case, a travel route element set is set using avertical straight line set and a horizontal straight line set, in whichthe vertical and horizontal intervals are equivalent to the first workwidth, for the area CA to be worked. Signs X1 to X9 are assigned asroute numbers to the travel route elements belonging to the horizontalstraight line set, and signs Y1 to Y9 are assigned as route numbers tothe travel route elements belonging to the vertical straight line set.

In FIG. 30, a spiral travel pattern is set so that the master harvester1 m and the slave harvester 1 s trace a double spiral line in thecounterclockwise direction, from the outside toward the inside. Assumethat the master harvester 1 m departs from the travel route elementhaving a route number of Y1, and the slave harvester 1 s departs fromthe travel route element having a route number of X1. In this case too,the route element selecting unit 63 is divided into the first routeelement selecting unit 631 and the second route element selecting unit632.

As illustrated in FIG. 30, the master harvester 1 m first travels alongthe travel route element having the route number Y1, which is selectedfirst by the first route element selecting unit 631. However, the travelroute element set illustrated in FIG. 30 is originally calculated usingthe first work width as an interval. Accordingly, the travel routeelement having the route number X1, which is selected first by thesecond route element selecting unit 632 for the slave harvester 1 shaving the second work width that is narrower than the first work width,has its positional coordinates corrected to compensate for thedifference between the first work width and the second work width. Inother words, the travel route element having a route number of X1 iscorrected toward the outside by an amount equivalent to 0.5 times thedifference between the first work width and the second work width (thisdifference will be called a “width difference” hereinafter) (FIG. 30,#01). The route numbers Y2, X8, and Y8, which correspond to the nexttravel route element selected in accordance with the travel of the slaveharvester 1 s, are corrected in the same manner (FIG. 30, #02, #03, and#04). Although the master harvester 1 m travels the travel routeelements from route number Y1 to route numbers X9 and Y9 as per theoriginal settings (FIG. 30, #03 and #04), the slave harvester 1 s istraveling on the outside of the travel route element having the routenumber X2, which is selected next, and thus the position of that travelroute element is corrected by an amount equivalent to the widthdifference (FIG. 30, #04). When selecting the travel route elementhaving the route number X3 for the slave harvester 1 s, the slaveharvester 1 s is already traveling on the travel route element havingthe route number X1, which is located on the outside of the route numberX3, and thus the position is corrected by an amount equivalent to 1.5times the width difference (FIG. 30, #05). In this manner, the positionsof the selected travel route elements are sequentially corrected so asto cancel out the difference between the first work width and the secondwork width in accordance with the number of travel route elementstraveled by the slave harvester 1 s that are present on the outside ofthe selected travel route element (FIG. 30, #06). Although the routemanaging unit 60 corrects the positions of the travel route elementshere, the correction may be carried out by the first route elementselecting unit 631 and the second route element selecting unit 632.

The examples of travel indicated in FIGS. 29 and 30 assume that thefirst route element selecting unit 631 and the second route elementselecting unit 632 are provided in the control unit 5 of the masterharvester 1 m. However, the second route element selecting unit 632 maybe provided in the slave harvester 1 s. In this case, it is preferablethat the slave harvester 1 s receive data indicating the travel routeelement set, and that the first route element selecting unit 631 and thesecond route element selecting unit 632 select their own next travelroute elements and make the necessary corrections to the positionalcoordinates while exchanging their respective selected next travel routeelements. A configuration is also possible in which the route managingunit 60, the first route element selecting unit 631, and the secondroute element selecting unit 632 are all provided in the communicationterminal 4, and the selected travel route elements are sent from thecommunication terminal 4 to the route setting unit 64.

(4) The control function blocks described in the foregoing embodiment onthe basis of FIG. 6 are merely examples, and the function units can bedivided further, or multiple function units can be combined, as well.Additionally, although the function units are allocated among thecontrol unit 5, the communication terminal 4, and the managementcomputer 100, which serve as higher-order control devices, thisallocation of the function units is also merely an example, and thefunction units can be allocated among the higher order control devicesas desired. The function units can also be allocated to otherhigher-order control devices as long as the higher-order control devicescan exchange data with each other. For example, all of the functions ofthe communication terminal 4 can be provided in the master harvester 1m. Additionally, although the other vehicle positional relationshipcalculating unit 56 is provided in the control unit of the harvester 1in the control function block diagram in FIG. 6, the other vehiclepositional relationship calculating unit 56 may be provided in thecommunication terminal 4. In this case, information such as the currentposition of the harvester 1, the travel route element currently beingtraveled on (selected), and the like is sent to the communicationterminal 4 from each harvester 1. Conversely, the other vehiclepositional relationship calculated by the other vehicle positionalrelationship calculating unit 56 is sent to the work state evaluatingunit 55 of each work vehicle 1. Furthermore, in the control functionblock diagram illustrated in FIG. 6, the work site data input unit 42,the outer shape data generating unit 43, and the area setting unit 44are provided in the communication terminal 4 as the first travel routemanaging module CM1. Furthermore, the route managing unit 60, the routeelement selecting unit 63, and the route setting unit 64 are provided inthe control unit 5 of the harvester 1 as the second travel routemanaging module CM2. However, the route managing unit 60 may instead beincluded in the first travel route managing module CM1. Likewise, theouter shape data generating unit 43, the area setting unit 44, and so onmay be included in the second travel route managing module CM2. Theentirety of the first travel route managing module CM1 may be providedin the control unit 5, and the entirety of the second travel routemanaging module CM2 may be provided in the communication terminal 4.Providing the greatest possible number of control function unitspertaining to travel route management in the portable communicationterminal 4 increases the freedom of maintenance and the like, which isconvenient. This allocation of function units is limited by the dataprocessing capabilities of the communication terminal 4 and the controlunit 5, the speed of communication between the communication terminal 4and the control unit 5, and so on.

(5) Although the travel routes calculated and set according to thepresent invention are used as target travel routes for autonomoustravel, the travel routes can also be used as target travel routes formanual travel. In other words, the present invention can be applied toboth autonomous travel and manual travel, and can of course also beapplied in a situation where autonomous travel and manual travel aremixed.

(6) The foregoing embodiment describes an example in which the fieldinformation sent from the management center KS includes a topographicalmap of the periphery of the field from the outset, and the accuracy ofthe outer shape and outer dimensions of the field is improved throughcircling travel executed along the borders of the field. However, theconfiguration may be such that the field information does not include atopographical map of the periphery of the field, or at least does notinclude a topographical map of the field, and the outer shape and outerdimensions of the field are calculated for the first time through thecircling travel. Additionally, the content of the field information,work plan manual, and so on sent from the management center KS, theitems input through the communication terminal 4, and so on are notlimited to those described above, and can be changed within a scope thatdoes not depart from the essential spirit of the present invention.

(7) The foregoing embodiment describes an example in which, asillustrated in FIG. 6, the rectangular route element calculating unit602 is provided in addition to the mesh route element calculating unit601, and the travel route element set, which is a parallel straight lineset covering the area CA to be worked, is calculated by the rectangularroute element calculating unit 602. However, the rectangular routeelement calculating unit 602 may be omitted, and linear back-and-forthtravel may be realized using the travel route elements corresponding toa mesh-shaped straight line set calculated by the mesh route elementcalculating unit 601.

(8) The foregoing embodiment describes an example in which, whenexecuting cooperative travel control, the parameters of the vehicletravel device group 71, the work device group 72, and so on of the slaveharvester 1 s are changed on the basis of a result of the monitoringcarried out by the monitoring party. However, the configuration may besuch that an image (a moving image, still images captured at setintervals, or the like) captured by a camera installed in the masterharvester 1 m or the slave harvester 1 s is displayed in a monitor orthe like installed in the master harvester 1 m, with the monitoringparty viewing the image, determining the work conditions of the slaveharvester 1 s, and changing the parameters of the vehicle travel devicegroup 71, the work device group 72, and so on. Alternatively, theconfiguration may be such that when the parameters of the masterharvester 1 m are changed, the parameters of the slave harvester 1 s arechanged in accordance therewith.

(9) Although the foregoing embodiment describes an example in whichmultiple harvesters 1 that execute work travel in cooperation with eachother travel autonomously according to the same travel pattern, theconfiguration can also be such that the autonomous travel is executedaccording to different travel patterns.

(10) Although the foregoing embodiment describes an example in which twoharvesters 1 execute cooperative autonomous travel, cooperativeautonomous travel by three or more harvesters 1 can also be realized bythe same work vehicle automatic traveling system and travel routemanaging device.

(11) As an example of the travel route element set, FIG. 3 illustrates atravel route element set in which multiple parallel dividing lines thatdivide the area CA to be worked into rectangular shapes serve as travelroute elements. However, the present invention is not limited thereto.For example, the travel route element set illustrated in FIG. 31 takescurved parallel lines as the travel route elements. In this manner, the“parallel lines” according to the present invention may be curved.Additionally, the “parallel line set” according to the present inventionmay include curved parallel lines.

(12) As an example of the travel route element set, FIG. 4 illustrates atravel route element set constituted by multiple mesh lines extending inthe vertical and horizontal directions that divide the area CA to beworked into a mesh. However, the present invention is not limitedthereto. In other words, the “mesh lines” according to the presentinvention need not be straight lines. For example, in the travel routeelement set illustrated in FIG. 32, the mesh lines in the horizontaldirection with respect to the diagram are straight lines, whereas themesh lines in the vertical direction with respect to the diagram arecurved. Additionally, in the travel route element set illustrated inFIG. 33, the mesh lines in the horizontal direction and the mesh linesin the vertical direction with respect to the diagram are both curved.In this manner, the mesh lines may be curved. Additionally, the meshline set may include curved mesh lines.

(13) In the foregoing embodiment, linear back-and-forth travel iscarried out by repeating travel along straight line-shaped travel routeelements and U-turn travel. However, the present invention is notlimited thereto, and the configuration may be such that back-and-forthtravel is carried out by repeating travel along curved travel routeelements, as indicated in FIGS. 31 to 33, and U-turn travel.

(14) In the foregoing embodiment, the harvester 1 executes circularharvesting first when executing harvesting work in the field. Note that“circular harvesting” refers to work for harvesting while travelingaround the inner side of the border line of the field. After thecircular harvesting, the area setting unit 44 sets the area on theoutside of the field traveled around by the harvester 1 as the outerperipheral area SA, and sets the area CA to be worked on the inside ofthe outer peripheral area SA. However, the present invention is notlimited thereto. In other words, the circular harvesting by theharvester 1 is not work that is necessary for the present invention.Additionally, the area setting unit 44 may be configured to set the areaCA to be worked without setting the outer peripheral area SA. Forexample, the area setting unit 44 may be configured to set the area CAto be worked in accordance with an input operation made by themonitoring party through the communication terminal 4.

INDUSTRIAL APPLICABILITY

The work vehicle automatic traveling system according to the presentinvention can be applied not only in the harvester 1, which is anormal-type combine serving as a work vehicle, but also in any workvehicle capable of automatically traveling while working in a work site.This includes other types of harvesters 1 such as autodetachable-typecombines and corn harvesters, tractors fitted with work devices such astilling devices, paddy work machines, and so on.

DESCRIPTION OF REFERENCE SIGNS

-   1: harvester (work vehicle)-   1 m: master harvester-   1 s: slave harvester-   4: communication terminal-   5: control unit-   41: touch panel-   42: work site data input unit-   43: outer shape data generating unit-   44: area setting unit-   50: communication processing unit-   51: travel control unit-   511: autonomous travel controlling unit-   512: manual travel controlling unit-   52: work control unit-   53: host vehicle position calculating unit-   55: work state evaluating unit-   56: other vehicle positional relationship calculating unit-   60: route managing unit-   63: route element selecting unit-   64: route setting unit-   70: communication processing unit-   80: satellite positioning module-   SA: outer peripheral area-   CA: area to be worked

The invention claimed is:
 1. A work vehicle automatic traveling systemfor a plurality of work vehicles that carry out work travelcooperatively in a work site while exchanging data, the systemcomprising: an area setting unit that sets the work site to an outerperipheral area, and an area to be worked on an inner side of the outerperipheral area; a host vehicle position calculating unit thatcalculates a host vehicle position; a route managing unit that manages atravel route element set and a circling route element set so as to becapable of readout, the travel route element set being an aggregate ofmultiple travel route elements constituting a travel route that coversthe area to be worked, and the circling route element set being anaggregate of circling route elements constituting a circling route thatgoes around the outer peripheral area; a route element selecting unitthat, based on state information, sequentially selects a next travelroute element, on which the work vehicle is to travel next, from thetravel route element set, or a next circling route element, on which thework vehicle is to travel next, from the circling route element set; andan autonomous travel controlling unit that executes autonomous travelbased on the next travel route element and the host vehicle position,wherein the route element selecting unit includes a cooperative routeelement selection rule employed when the plurality of work vehiclescarry out work travel cooperatively in the area to be worked, and anindependent route element selection rule employed when one of the workvehicles acts as an independent work vehicle and carries out independentwork travel in the area to be worked; and when the independent workvehicle is carrying out independent work travel in the area to beworked, and a work vehicle aside from the host vehicle is carrying outcircling travel based on the circling route element or is stopped, theroute element selecting unit of the independent work vehicle selects thenext travel route element based on the independent route elementselection rule.
 2. The work vehicle automatic traveling system accordingto claim 1, wherein: the travel route element set is a mesh line setconstituted by mesh lines that divide the area to be worked into a mesh;points where the mesh lines intersect are set as route changeable pointswhere a route of the work vehicle is permitted to be changed; thecooperative route element selection rule comprises selecting the nexttravel route element so that a compound spiral-shaped travel trajectorycreated by a plurality of spiral-shaped travel trajectories made by thework vehicle covers the area to be worked; and the independent routeelement selection rule comprises selecting the next travel route elementso that the spiral-shaped travel trajectory made by the independent workvehicle covers the area to be worked.
 3. The work vehicle automatictraveling system according to claim 1, wherein: the travel route elementset is a parallel line set constituted by mutually-parallel lines thatdivide the area to be worked into rectangular shapes; movement from oneend of one travel route element to one end of another travel routeelement is executed through U-turn travel by the work vehicle; thecooperative route element selection rule comprises excluding a presenttravel route element where a work vehicle aside from the host vehicle islocated, and a travel route element adjacent to the present travel routeelement, from being selected as the next travel route element; and theindependent route element selection rule comprises excluding a travelroute element moving toward the work vehicle aside from the hostvehicle, located in the outer peripheral area, from being selected asthe next travel route element.
 4. A work vehicle automatic travelingsystem for a plurality of work vehicles that carry out work travelcooperatively in a work site while exchanging data, the systemcomprising: a host vehicle position calculating unit that calculates ahost vehicle position; a route managing unit that calculates a travelroute element set, the travel route element set being an aggregate ofmultiple travel route elements constituting a travel route covering thearea to be worked, and stores the travel route element set so as to becapable of readout; and a route element selecting unit that selects anext travel route element, which is to be traveled next, sequentiallyfrom the travel route element set, based on the host vehicle positionand a work travel state of another work vehicle of the plurality of workvehicles, wherein: an other work vehicle positional relationshipindicating a positional relationship between the host vehicle andanother work vehicle of the plurality of work vehicles is included inthe work travel state of the another work vehicle; the system furthercomprises an other work vehicle positional relationship calculating unitthat calculates the other work vehicle positional relationship; theother work vehicle positional relationship calculating unit calculatesan estimated contact position between the plurality of work vehiclesbased on the other work vehicle positional relationship; and when theestimated contact position has been calculated, a work vehicle of theplurality of work vehicles that will pass the estimated contact positionat a later time is temporarily stopped.
 5. The work vehicle automatictraveling system according to claim 4, wherein: the other work vehiclepositional relationship calculating unit calculates the estimatedcontact position based on the other work vehicle positional relationshipand on the travel route elements where the plurality of work vehiclesare traveling.
 6. A work vehicle automatic traveling system for aplurality of work vehicles that carry out work travel cooperatively in awork site while exchanging data, the system comprising: one or moreprocessors programmed and/or configured to: set the work site to anouter peripheral area, and an area to be worked on an inner side of theouter peripheral area; calculate a host vehicle position; manage atravel route element set and a circling route element set so as to becapable of readout, the travel route element set being an aggregate ofmultiple travel route elements constituting a travel route that coversthe area to be worked, and the circling route element set being anaggregate of circling route elements constituting a circling route thatgoes around the outer peripheral area; based on state information,sequentially select a next travel route element, on which the workvehicle is to travel next, from the travel route element set, or a nextcircling route element, on which the work vehicle is to travel next,from the circling route element set; execute autonomous travel based onthe next travel route element and the host vehicle position; include acooperative route element selection rule employed when the plurality ofwork vehicles carry out work travel cooperatively in the area to beworked, and an independent route element selection rule employed whenone of the work vehicles acts as an independent work vehicle and carriesout independent work travel in the area to be worked; and select thenext travel route element for the independent work vehicle based on theindependent route element selection rule when the independent workvehicle is carrying out independent work travel in the area to beworked, and a work vehicle aside from the host vehicle is carrying outcircling travel based on the circling route element or is stopped. 7.The work vehicle automatic traveling system according to claim 6,wherein: the travel route element set is a mesh line set constituted bymesh lines that divide the area to be worked into a mesh; points wherethe mesh lines intersect are set as route changeable points where aroute of the work vehicle is permitted to be changed; the cooperativeroute element selection rule comprises selecting the next travel routeelement so that a compound spiral-shaped travel trajectory created by aplurality of spiral-shaped travel trajectories made by the work vehiclecovers the area to be worked; and the independent route elementselection rule comprises selecting the next travel route element so thatthe spiral-shaped travel trajectory made by the independent work vehiclecovers the area to be worked.
 8. The work vehicle automatic travelingsystem according to claim 6, wherein: the travel route element set is aparallel line set constituted by mutually-parallel lines that divide thearea to be worked into rectangular shapes; movement from one end of onetravel route element to one end of another travel route element isexecuted through U-turn travel by the work vehicle; the cooperativeroute element selection rule comprises excluding a present travel routeelement where a work vehicle aside from the host vehicle is located, anda travel route element adjacent to the present travel route element,from being selected as the next travel route element; and theindependent route element selection rule comprises excluding a travelroute element moving toward the work vehicle aside from the hostvehicle, located in the outer peripheral area, from being selected asthe next travel route element.
 9. A work vehicle automatic travelingsystem for a plurality of work vehicles that carry out work travelcooperatively in a work site while exchanging data, the systemcomprising: one or more processors programmed and/or configured to:calculate a host vehicle position; calculate a travel route element set,the travel route element set being an aggregate of multiple travel routeelements constituting a travel route covering an area to be worked, andstores the travel route element set so as to be capable of readout; andselect a next travel route element, which is to be traveled next,sequentially from the travel route element set, based on the hostvehicle position and a work travel state of another work vehicle of theplurality of work vehicles, wherein: an other work vehicle positionalrelationship indicating a positional relationship between the hostvehicle and another work vehicle of the plurality of work vehicles isincluded in the work travel state of the another work vehicle; the oneor more processors are programmed and/or configured to calculate theother work vehicle positional relationship; the one or more processorsare programmed and/or configured to calculate an estimated contactposition between the plurality of work vehicles based on the other workvehicle positional relationship; and when the estimated contact positionhas been calculated, a work vehicle of the plurality of work vehiclesthat will pass the estimated contact position at a later time istemporarily stopped.
 10. The work vehicle automatic traveling systemaccording to claim 9, wherein: the one or more processors are programmedand/or configured to calculate the estimated contact position based onthe other work vehicle positional relationship and on the travel routeelements where the plurality of work vehicles are traveling.